growing strawberries in wisconsin

B R I A N R . S M I T H , D A N I E L L . M A H R , P A T R I C I A S . M C M A N U S , T E R Y L R . R O P E R

GROWING STRAWBERRIESIN WISCONSIN

A1597

Fragaria x ananassa

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CONTENTS

The strawberry plant . . . . . . . . . . . . . . . . 2

Growth and fruiting habit . . . . . . . . . . . . . 3

Cultivar selection . . . . . . . . . . . . . . . . . . 3

Site and soil requirements . . . . . . . . . . . . . 6

Planting . . . . . . . . . . . . . . . . . . . . . . . 6

Care of plants . . . . . . . . . . . . . . . . . . . . 9

Harvest and handling . . . . . . . . . . . . . . . 11

Insect pests . . . . . . . . . . . . . . . . . . . . . 12

Diseases . . . . . . . . . . . . . . . . . . . . . . . 16

Problem solving . . . . . . . . . . . . . . . . . . 21

Related publications . . . . . . . . . . . . . . . 23

Nurseries . . . . . . . . . . . . . . . . . . . . . . 24

StrawberriesI N W I S C O N S I N

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THE STRAWBERRY PLANT

S trawberries are the most

popular small fruit grown in home gardens

throughout the state. Strawberries are quite

easy to grow. They are adapted to most soil

types and do not typically

require an elaborate

spray program. One

plant can yield 1 to

11⁄2 quarts of fruit if

cared for properly. This

publication describes how to

plant, tend, and harvest

strawberries for bountiful production.

The strawberry is an herbaceous perennial. Theperennial portion of the plant is the crown, whichis a shortened stem. The crown produces roots,leaves, runners (stolons), branch crowns, andflowers. As the crown grows it elongatesupward, and thus tends to “grow out” of the soil.New roots are formed progressively higher onthe crown. Strawberry plants are shallow rootedwith 50 to 90% of the root volume in the top 6inches of soil. Be careful to not disturb the rootswhen cultivating and to keep the soil in the rootzone from drying out.

Strawberry plants spread by means of runners(stolons). Stolons are initiated in response to daylength. At the second node of the stolon, leaves

and roots are initiated, forming a daughter plant.Once the daughter plant has rooted, the stoloncan be cut and the new plant will continue tothrive. Rooting usually takes 2 to 3 weeks.

Branch crowns are also formed from axillary budson the main crown. Unlike daughter plants,branch crowns do not form their own roots, butthey are otherwise identical to the main crownaxis and daughter plants. A branch crown pro-duces leaves and flowers independently of themain crown. As more branch crowns are pro-duced, the crown becomes crowded, inefficient,and unproductive. This is one factor that deter-mines when a strawberry planting must bereplaced.

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GROWTH AND FRUITINGHABIT

Junebearing cultivarsThe most common type of strawberries inWisconsin are Junebearing. These plants bearone large crop of fruit each year after the firstyear in mid-June to early July, depending onlocation in the state. Plantings of Junebearingstrawberries will be productive for 3 to 6 years ifgiven proper care.

Everbearing cultivarsThese plants bear a small early summer cropand may fruit one or more additional times untilthe first heavy freeze. Everbearing cultivarsrequire different planting systems and moreattention than Junebearing cultivars. You canexpect fruit from mid- to late summer the year ofplanting. Plantings of everbearing strawberriesshould be replaced every other year.

Day-neutral cultivarsDay-neutral cultivars produce fruit and runnerscontinuously during the growing season if cooltemperatures and sufficient moisture prevail.These plants require full sun to produce a cropjust like other strawberry types. Day-neutralcultivars can be allowed to start setting fruit inJuly the year of planting. Currently availableday-neutral cultivars are not as cold hardy as thehardiest Junebearers and everbearers. Plantingsof day-neutral strawberries should be replacedeach year.

CULTIVAR SELECTIONTo help ensure success with your berries it isimportant to select a cultivar (cultivated variety)suited to your particular needs and growingconditions. Various cultivars are good for freez-ing, fresh use, or both. You will get the most

FIGURE 1. Relative percentage of rootsgrowing in the top 12 inches of soil.

FIGURE 2. Strawberry plant with rooted daughter plant.

0–3 inches25–50%

3–6 inches25–40%

6–12 inches10–50%

youngest roots

mother plant

daughter plant

oldest roots

runnercontinuation

runner (stolon)crown

I N W I S C O N S I N

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berries in any one picking season fromJunebearers. Everbearing and day-neutral culti-vars produce a smaller but more constant supplyof berries for fresh eating and desserts through-out most of the growing season. Cultivars alsovary in the degree of disease resistance or toler-ance, cold hardiness, yield, and ripening season.

The following cultivars are grouped in order ofripening. The letters N and S indicate the region(northern and southern, respectively) the cultivaris best suited for.

Junebearing cultivarsEarly season

Annapolis (N&S) Fruit is attractive, large,medium red, and firm, but somewhat bland. Forfresh use. Quite productive cultivar. Good resist-ance to red stele.

Crimson King (N) Fruit is large but somewhatsoft and marginal in quality. Good for fresh useor processing. Vigorous and productive cultivar.Shows good tolerance to leaf scorch and leaf spot.Resistant to several races of red stele. Very hardy.

Earliglow (S) Fruit is firm and has excellent fla-vor. Fair for freezing. Moderately productive cul-tivar. Resistant to root diseases, moderatelyresistant to leaf diseases, and tolerant of botrytis.

Lester (S) Attractive, large berries are firm andhave very good flavor. For fresh use or freezing.High vigor and plant production. Resistant to redstele and leather rot, and has a high tolerance forgray mold.

Early midseason

Honeoye (N&S) Top commercial cultivar inWisconsin. Large, attractive fruit is good for freshuse and excellent for freezing. Highly productivecultivar. Tolerant of leaf powdery mildew andbotrytis gray mold, but susceptible to red steleand angular leaf spot. Very hardy.

Raritan (S) An older cultivar requiring a littleextra care due to lower vigor and less diseaseresistance. The excellent quality, flavorful fruit isglossy, bright red, and medium-large. Very easyto harvest. Use fresh; not for freezing.

Redchief (S) Medium-large berries are firm,glossy, and deep red with good flavor and consis-tency. For fresh use or processing. Resistant tomildew, red stele, and leaf scorch. Tolerant toVerticillium wilt.

Midseason

Cavendish (N&S) Dark red fruit is firm andvery large. Flavor is slightly superior toAnnapolis. For fresh use. Very high yield poten-tial. Resistant to red stele and tolerant of botrytis.

Glooscap (N&S) Large fruit is dark, glossy redand has good flavor. For fresh use or processing.Plant is very productive and vigorous. Producesmany runners. Resistant to leaf scorch and leafspot, but susceptible to soilborne diseases.

Kent (N&S) Berries are firm, large, and glossy;milder in flavor and lighter in color thanHoneoye. Excellent for all uses. Plant is highyielding and vigorous, but produces few runners.

Strawberries

FIGURE 3. Northern and southernwinterhardiness designations for Wisconsin.

N

S

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Late midseason

Jewel (S, for trial N) Very attractive, medium-red, glossy fruit has excellent flavor. For fresh useor freezing. High yield potential. Good toleranceto botrytis gray mold and post-harvest fruit rots.

Mira (for trial N&S) New from Nova Scotia.Large, blocky-conical fruit is a bright medium tolight red in color and has a mild flavor. Resistantto most foliar diseases and most races of redstele. Good runner production.

Mesabi (for trial N&S) New from University ofMinnesota and USDA. Glossy, bright red fruit islarge and very firm. Fruit has very good flavor.Vigorous plants may have limited runner produc-tion. Hardy.

Seneca (N&S) Attractive fruit is very large andfirm, but has only average flavor. For fresh use orfreezing. Vigorous plant growth. Average diseasetolerance.

Late season

Lateglow (S, for trial N) Very large, symmetri-cal, pale fruit has excellent flavor and adequatefirmness. For fresh use or freezing. Excellentvigor and disease tolerance.

Sparkle (N&S) High-quality, flavorful berry.Excellent for freezing. Late berries tend to besmall and soft. Susceptible to virus disease buttolerant to red stele. Very hardy.

Winona (S, for trial N) A new cultivar from theUniversity of Minnesota and USDA. Attractive,very large, glossy scarlet fruit is firm with goodtexture and quality. Resistant to most leaf dis-eases and several root diseases. Vigorous plantshave good runner production.

Everbearing cultivarsFort Laramie (N) Medium-sized, soft fruit isdark red and sweet. Plants are vigorous and win-ter hardy. Dense, leathery foliage is somewhatresistant to leaf spot.

Ogallala (N) Medium-sized fruit is dark red andsomewhat soft but highly flavored. Good forfreezing. Plants are hardy, vigorous, and produc-tive. Resistant to leaf spot and tolerant of drought.

Ozark Beauty (N&S) Large, moderately firmfruit is necked and glossy and has a mild flavor.For fresh use or freezing. Plants are productive,vigorous, and produce runners freely. Resistant toleaf spot and leaf scorch.

Day-neutral cultivarsDay-neutral cultivars will need to be replantedeach year as the plants will not survive mostWisconsin winters.

Fern (N&S) Good quality, medium-large fruit isred and conical. For fresh use. Good repeatbloom. Tolerant to leaf spot and susceptible tored stele, leaf scorch, and Verticillium wilt.

Selva (N&S) Very large, conical fruit is mediumred and should be allowed to fully ripen on theplant for full flavor. Vigorous, productive plants.

Seascape (N&S) Large, conical fruit is mediumfirm with dark red skin and flesh. Very good fla-vor. For fresh use. Resistant to Verticillium wiltand leaf scorch, susceptible to leaf spot.

Tribute (N&S) Firm fruit has good flavor butlacks intense red coloring. For fresh use or freez-ing. Quite vigorous, producing medium-sizedplants. Resistant to red stele and Verticilliumwilt; tolerant of botrytis.

Tristar (N&S) Firm, small fruit has good flavorand intense color. For fresh use or freezing.Flavor development lags behind color so waituntil fruit is fully colored before harvesting.Moderate vigor, producing smaller plants thanTribute. Moderately resistant to red stele andresistant to Verticillium wilt.


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Plant sourceAvoid the temptation to start new plantings froman existing planting. These plants may harbordiseases and insects that are not readily apparent.Purchase plants from a reliable nursery to be surethey are true to name, vigorous, healthy, and dis-ease free. Disease-free plants grow better, pro-duce more fruit, and live longer. But remember,although these plants start out disease free, theyare not immune to diseases. You will still need totake precautions to avoid infecting the plantingwith viruses and other diseases that will weakenthe plants. Many local and mail-order nurseriessell high-quality strawberry plants.

Plant numbersFifty plants should produce enough fresh fruitfor a family of four. Extra plants will provideberries for home freezing, jellies, and jams.

SITE AND SOILREQUIREMENTSChoose a convenient location in full sun.Strawberries grown in shade are less productive.Avoid low spots where water often stands. Suchspots have poor soil drainage and may be frostpockets where cold air collects on frosty nights.

You can grow strawberries successfully on manydifferent kinds of soil. A sandy loam is ideal,offering good drainage with adequate water-holding capacity. Avoid poorly drained clay soils.

FertilizationPreplant fertilizer needs will depend on the pres-ent fertility of the soil. To determine initial soilfertility, you should have the soil tested. A soiltest will tell you how much lime, organic matter,and fertilizer your soil may need. Most soils ben-efit from a preplant application of organic matter.For more information on fertility see Extensionpublication Fertilizing Small Fruits in the HomeGarden (A2307).

Site preparationSite preparation should begin at least one yearbefore planting. This is the best time to controlperennial weeds since removing them after plant-ing is extremely difficult.

In the spring before planting, work the soil sothat it is loose to a depth of 6 to 8 inches. Addany lime or fertilizer recommended by the soiltest report. Avoid planting strawberries in thesame space where they grew previously. Rotategarden spots with other crops. Some crops har-bor diseases that strawberries are susceptible to.If possible, avoid rotating strawberries into areaswhere the following crops were grown: raspber-ries, blueberries, tomatoes, potatoes, peppers,eggplants, and vining crops such as cucumberand watermelon.

PLANTING

Protect plantsAfter receiving plants from a nursery, do notallow them to become too warm. Be sure to keepthe roots moist. If the plants arrive before theycan be planted, you have two storage options:heeling in (temporary planting) and refrigeration.

To heel in plants, remove them from the shippingbags immediately on arrival. Using a spade, dig aV-shaped trench 6 to 8 inches deep in a cool loca-tion. Lay the strawberry plants 2 inches apartalong one side of the trench, perpendicular to thetrench length. Fill the trench with soil and thenwater the plants thoroughly. You can keep plantsthis way for several weeks.

If you need to keep plants in refrigerated storage,leave them in the shipping bags. Plants should bekept relatively dry until planting. Moisture fromthe plants themselves will provide sufficienthumidity within the bags to keep them alive andyet prevent rotting. If plants appear unusuallydry, wrap a damp paper towel around the roots.Plants can be kept in the refrigerator for up to6 weeks. Don’t store strawberry plants with fruitsuch as apples or pears.

When to plantStrawberry plants should be planted in earlyspring as soon as the soil can be thoroughlyworked. Properly stored plants may be plantedas late as mid-June if soil moisture is good andirrigation is available. Strawberries planted latewill have inferior yield the first season comparedto stock planted early.

Setting plantsJust before planting, remove dry and old leavesfrom the crown and any attached runner remains.Leave two or three fairly well-developed leaves.

Using a trowel or spade, open a hole in the soildeep enough for the roots to hang straight.Spread out the roots for good soil contact. Placethe plants so that only the roots and base of thecrown will be covered with soil. Press soil firmlyto establish contact with the roots and to elimi-nate air pockets.

Plant spacing and trainingProper plant spacing and training will maximizefruit production and reduce some pest problems.The goal of all strawberry planting systems is tooptimize plant density. Too many or too fewplants will reduce fruit yield. Most fruit are pro-duced along row edges.

The two basic methods of han-dling runner plants (new plantsgrowing from the parentplants) are the matted row sys-tem and the hill system. Manyvariations are possible withinthese two basic systems. Youcan vary between-row spacing,within-row plant spacing, run-ner plant density, and rowwidth (width you allow plantsto fill in a row) for maximumproduction or to suit your par-ticular requirements.

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FIGURE 4. Technique for planting strawberries.

FIGURE 5. Proper planting depth.

too shallow

too deepcorrect planting depth

1 2 3 4

Matted row system. This system requires theleast amount of labor and is best suited forJunebearing cultivars. With this system, runnerplants are allowed to root at random within therow until they form a solid mat of a certainwidth. To maximize yields, limit the row widthto 12 to 15 inches and maintain between-rowspacing at about 36 inches. A rotary tiller can beused to maintain row widths. Within-row plantspacing for vigorous cultivars such as Honeoyeand Sparkle should be 24 to 30 inches. Cultivarssuch as Kent may be planted 14 to 24 inchesapart within rows.

Hill system. This system offers maximum pro-duction from a small space and is ideal for ever-bearing and day-neutral cultivars. Plant bedscontain three rows spaced 12 inches apart; plantswithin the rows are spaced 12 inches apart.Stagger the middle row as shown in the diagrambelow. Leave 30 to 36 inches between each three-row bed. Cut off all runners as soon as they arevisible. Continue to remove runners for the life ofthe planting to encourage large crowns, largerberries, and higher yields on the original plant.


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FIGURE 6. Matted row system(for Junebearing cultivars).

FIGURE 7. Hill system (for everbearing and day-neutral cultivars).

36"

30–36"

12"

12–15"

12"

15–30"

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CARE OF PLANTS

General careIrrigation. Water is a key ingredient to success-ful strawberry growing. Depending on soil type,strawberries require about 1 inch of water fromirrigation or rainfall every week during thegrowing season. Since most of the roots are nearthe soil surface, frequent irrigations of lesseramounts are best. Irrigation must continue afterharvesting Junebearing strawberries. If theweather turns hot and dry during harvest, dailywatering will help produce good fruit size andwill maintain berry firmness.

Cultivation. Begin to cultivate within a fewdays after planting to keep the soil loose and toprevent weed growth. Continue cultivatingthroughout the growing season to kill the weedsand to keep the soil in good condition. Hoeingand hand weeding will be necessary to removethe weeds growing between the plants.Remember that about 50% of a strawberry plant’sroots are in the top 3 inches of soil and 90% arein the top 6 inches. Shallow cultivation will limitroot damage.

Weed control. Weeds compete directly withstrawberry plants for light, water, and nutrients.They also interfere with insect and disease con-trol. If you allow weeds to flower and set seeds,weed problems will worsen each year. Therefore,weeds must be controlled at all times. By culti-vating the soil with a sharp hoe while at thesame time removing weeds, you will greatly ben-efit the planting.

The use of herbicides (weed-killing chemicals) isnot recommended for small strawberry plant-ings. Cultivation, mulching, or hoeing providegood weed control.

A summer mulch will help control weeds. Waitto apply the mulch until after the runner plantshave rooted. Two types of mulch are available forweed control in strawberry plantings: organicand synthetic. Organic mulches are satisfactory

for all strawberry planting systems while syn-thetic mulches are better suited for the hill system.

Organic mulches include straw, sawdust, shred-ded bark, crushed corn cobs, and chopped hay.In addition to controlling weeds, organicmulches also hold moisture, keep berries clean,add organic matter to the soil and maintain acooler, more even root temperature (especiallyimportant for everbearers and day-neutrals).When applying mulch, spread it no deeper than3 inches over the soil surface.

Organic mulch may reduce the amount of nitro-gen available to plants, so you should spreadsupplemental fertilizer over the mulch at the rateof 1⁄4 cup of ammonium nitrate (33-0-0) perbushel of mulch. Don’t disturb mulch afterapplying nitrogen.

Black plastic is a typical synthetic mulch. It ismore appropriate for everbearing and day-neutralcultivars. Lay down black plastic at planting. Cuta small cross-shaped slit for each plant. Untilplants produce a good canopy the black plasticmay overheat the soil, which will slow plantgrowth and fruit production. To prevent over-heating, spread a light straw mulch over theblack plastic until the plants grow larger andcover most of the plastic.

Winter mulch. Strawberries are not sufficientlyhardy to tolerate all winter weather conditions.Damage to the crown can be expected if the tem-perature drops below 18°F. Applying a goodloose mulch will protect the plants against cold.Cover plant rows with clean (free of weed seed)marsh hay, sudangrass, coarse wheat or ryestraw, or other suitable material when theground has frozen about 1⁄2-inch deep, generallywhen the temperature drops to 20°F (mid- to lateNovember). Apply enough to provide a settledmulch 2 to 4 inches deep.

Tree leaves make poor winter mulch. When wet-ted, they tend to mat and may smother straw-berry plants underneath. Oat straw is alsounsuitable because it often contains many weedseeds and breaks down too quickly.


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Care during the first yearBlossom removal. On Junebearing cultivars,pinch out all blossom clusters the first year. Thispractice allows production of a large, vigorousplant and healthy runners instead of fruit. Fruitproduction will be greater the second year ifflowers are removed the first year.

On everbearers and day-neutrals, remove allblossoms for the first 6 to 8 weeks after planting.If flowers are not removed during this establish-ment period, the plants become stunted, reducinglater yields. After plants are established, allow allflowers to develop into fruit. If plants are keptfor a second year, allow all flowers to develop totake advantage of the long fruiting season uniqueto these types.

Fertilization of Junebearing cultivars. Forstrong runner plants, apply nitrogen when plantsbegin to form runners, about mid-June.Applications of 1 pound (2 cups) of ammoniumnitrate per 100 feet of row should be sufficient.Brush off any fertilizer that falls on the leaves.Water plants after fertilizing to dissolve fertilizerand wash it into the soil.

Strawberry plants start forming blossom buds fornext year’s crop beginning in late August. Theyneed to have adequate fertility available at thattime to produce many flower buds. Therefore,apply nitrogen a second time over the row inearly to mid-August at 11⁄2 times the earlier rate.

For more detailed fertilization suggestions, referto Extension publication Fertilizing Small Fruits inthe Home Garden (A2307).

Tissue testing is another method used to analyzenutritional requirements. For more information,contact your county Extension office.

Fertilization of everbearing and day-neutral cultivars. These two cultivar types re-quire a different fertilization regime fromJunebearing strawberries. Generally day-neutralcultivars need the most fertilizer because ofalmost constant fruiting. Everbearing cultivarsdiffer widely in ability to produce multiple crops.Therefore, for everbearing and day-neutral types,fertilize every month they’re in flower or arefruiting. Apply 1 to 2 pounds (2 to 4 cups) ofammonium nitrate per 100 feet of row. In coolerareas of Wisconsin during the summer, someday-neutrals may require fertilization everymonth from June through September. Spread thefertilizer in a ring or band at least 3 inches awayfrom the plant.

Care after the first yearMulch removal. Remove mulch in the spring assoon as new growth appears from the crown.Wait until the average nighttime low remainsabove 20°F. Once you’ve removed the mulch,you’ll need to protect plants on frosty nights.

Frost control. Early spring frosts are a hazardfor strawberries. If the mulch is still in the plant-ing, it can be raked back over the plants for thenight. Or cover the plants with a tarp or spun-bonded polyester row cover. The goal is to retainheat from the soil under the tarp. As the straw-berry plants and flowers develop, they becomeincreasingly vulnerable to frosts. Once the flow-ers are visible, they will be damaged if tempera-tures fall below 28°F.

Cultivar selection can also help to avoid frostproblems. Lateglow, Seneca, and Sparkle usuallybloom late in the season and escape frost.Everbearing or day-neutral cultivars quicklyproduce new flower clusters if the first flowersare injured.

FIGURE 8. Plants covered with mulch forwinter protection.

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Fertilization. Do not fertilize Junebearers earlyin the spring before harvest. Fertilizer increasesvegetative vigor of the plants and may reduceyield and cause soft berries. One possible excep-tion to “no spring fertilization” is when straw-berries are grown on a light sandy soil andplants appear deficient due to rapid leaching ofnutrients in late fall and early spring or if somewinter injury has occurred. See the section onrenovation for fertilizer recommendations.

Renovating matted row plantings(Junebearing strawberries). For continued produc-tion in succeeding years, you must begin reno-vating Junebearing strawberry plantings imme-diately after harvest. To renovate, follow thesesteps:

1.Remove weeds. Keep weeds out of theplanting by cultivation and hand weeding. Tohelp maintain a weed-free planting, a summermulch can be placed in the aisles betweenrows. Be sure to leave the row free of mulch sonew runner plants can fill in to restore properplant row width.

2.Mow the foliage. If leaf diseases are evidentthey may be lessened by removing the foliagewith a lawn mower. Set mower height at apoint where the leaves are cut off while notdamaging the crown.

3.Narrow the rows. Strawberries spread bysending out runners. To maintain aislesbetween rows, plants must be removedbetween the rows. A row width of 12 to 15inches is optimum. A rotary tiller, sharp hoe,or shovel can be used to keep the rows narrowand cultivate between the rows. Cultivationalso incorporates any organic mulch materialsleft over from winter.

4.Fertilize. Apply nitrogen fertilizer at the rateof 1⁄2 to 3⁄4 pound actual nitrogen per 100 feet ofrow. This would be about 6 pounds of 10-10-10fertilizer, 3 pounds of ammonium sulfate(21-0-0), or 2 pounds ammonium nitrate (33-0-0).

5.Irrigate. Continue watering after harvest tokeep the planting healthy. Flower buds for thenext year’s crop are formed after harvest, sokeeping the planting vigorous during thisperiod is critical for next year’s crop.Strawberries should receive at least 1 inch ofwater per week.

6.Fertilize again. Apply additional nitrogenfertilizer in mid-August to help flower budformation. About 3 pounds of 10-10-10 fertil-izer per 100 feet of row, or 11⁄2 pounds ammo-nium sulfate or 1 pound ammonium nitrateshould be adequate.

Renovating hill system plantings (everbearing and day-neutral cultivars). Set neweverbearing plants every other year and day-neutrals annually using nursery-grown plants.As described earlier, prepare the site before eachplanting. Keep the area weed free between plant-ings by cultivation and hand weeding.

HARVEST AND HANDLING

HarvestingBerries should be picked as often as every otherday to maintain quality. Do not allow overripeberries to remain on the plants. Overripe berriesinvite insect and disease problems and some cul-tivars develop off-flavors when overripe.

To pick strawberries, cradle the fruit in yourhand, pinch the stem between the thumb andforefinger, and pull with a twisting motion. Thecaps should be picked along with the fruit. Pickall of the ripe berries, both the large and smallfruit. Place the fruit into shallow containers nomore than 3 inches deep. Deeper containers willlead to bruising. Quart and pint containers aretypically used.

Storing fruitRipe strawberries are very perishable. For maxi-mum storage life, the fruit must be cooled imme-diately after harvest. If you have a large quantityof fruit to cool, spread it out in the refrigerator.After the berries have cooled, the containers canbe placed in vented plastic bags. The higherhumidity will keep the fruit firmer in storage.Fruit may be stored up to 4 days if refrigeratedpromptly. Do not wash berries before storage aswashing leads to more fruit rots. However, besure to wash fruit in running water before eatingor processing.


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INSECT PESTSAlthough there are several insect and mite pestsof strawberry, generally damage is relatively min-imal. However, in some locations or during someyears they can cause serious damage if not prop-erly managed. The best approach to managingstrawberry insects involves being able to recog-nize important pests and their damage, andknowing a little about their life cycles and bestmethods for control. Check the planting weeklythroughout the growing season for symptoms ofunusual plant growth or signs of specific pestactivity. If you find pests that you don’t recog-nize, have them identified so that you can choosethe best control options. Ideally, you will useinsecticides only when needed, when pest pres-sures warrant attention and non-chemical meth-ods are not available.

A second approach to managing strawberryinsects is the use of preventive insecticides. Thisoption is acceptable where there has been aknown history of significant pest pressures.Standard times for applying preventive insecti-cides are just before bloom, just after bloom, andafter harvest and renovation.

If it is necessary to use both an insecticide and afungicide, in many cases these products can bemixed together and sprayed at the same time.However, in some cases there may be pesticideincompatibility; carefully read the labels of bothproducts before attempting unfamiliar mixtures.

For specific insecticide recommendations, consultStrawberry Pest Management for Home Gardeners(A2127). This publication is revised as needed.Because pesticide information frequentlychanges, you should refer to the most recent ver-sion of the publication and to the label directionson the container.

AphidsSeveral different kinds ofaphids feed on strawberries.Most are small, greenish, soft-bodied insects which may ormay not have wings. Aphidsbegin to feed soon after birth by sucking plantjuices, thus reducing plant vigor and yield. Moreimportant, aphids spread certain virus diseasesand, therefore, should be controlled throughoutthe season. Aphids are usually more abundantearly in the season.

CutwormsCutworms can cause severedamage by cutting off plantsat or below ground level, aswell as by feeding on foliageand fruit. The worms are stout,smooth, greasy looking, andusually curl up when dis-

turbed. Cutworms feed on plants at night andhide near the plants in the soil during the day.They are usually a problem in grassy or weedyplantings or if sod areas are spring plowed andplanted to strawberries. Close observation with aflashlight at night may be necessary to confirmcutworm activity. Cutworms can be controlledwith several insecticides. In addition to sprayableformulations, granular baits, with an incorpo-rated feeding attractant, are also available for cut-worm control.

Cyclamen miteThe cyclamen mite is nearly impos-sible to see with the unaided eye,but the damage it causes is quitenoticeable—plants become verystunted, older leaves are cuppedand new leaves are extremely

small, wrinkled, and noticeably off-color. Heavyinfestations will result in small, off-color, andleathery fruit. The mites generally feed in thecrown area and are not abundantly found on

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exposed leaves or fruit except when the popula-tions are very high. Commercial growers shouldrefer to Extension publication Strawberry andRaspberry Pest Management in Wisconsin (A1934)for recommendations on chemical control. Noeffective pesticides are available to home garden-ers. The most appropriate approach for homegardeners is to destroy the infested planting,carefully clean up all the plant residues, andreplant the following year with uninfested plants.

Always start new plantings with clean stock. Donot use daughter plants from mother plants sus-pected to be infested, because mites readily crawlfrom plant to plant. Young plants can appearhealthy but still be infested.

Flea beetlesThese small (1⁄16 inch) blue-blackmetallic beetles readily jump whendisturbed. Flea beetles feed onleaves, flowers, and young fruit.Damaged leaves are riddled with

small holes. These insects are usually not a severeproblem in weed-free strawberries or strawber-ries isolated from weedy adjacent areas.

LeafhoppersMany species of leafhoppers infeststrawberries, but the potatoleafhopper causes the most dam-age. The potato leafhopper iswedge-shaped, light green in color,about 1⁄8 inch long and the adultsquickly fly when disturbed. Theyoung nymph is lighter in color

and lacks wings. You can readily identify it by itshabit of moving sideways. Both adults andnymphs feed on the underside of leaves suckingplant juices. They also inject a toxic saliva intothe plant which causes cell breakdown. As aresult, leaves become curled and stunted.

The potato leafhopper attacks many types ofplants. It frequently becomes more of a problem

in strawberries after surrounding vegetation hasbeen stressed or damaged. For example, themowing of an adjacent alfalfa field or roadsideright-of-way can force leafhoppers to seek foodin managed plantings such as strawberry.Similarly, as vegetation dries in mid to late sum-mer, leafhoppers will be attracted to irrigated orotherwise more healthy plants. The most severedamage from leafhoppers may appear during theestablishment year.

Plant bugsPlant bugs, orlygus bugs, causestunted berrieswith a concentra-tion of seeds atthe tip. Damagedberries are called“cat-face” berries.

Plant bugs are the most important insect problemof strawberries grown in Wisconsin. They suckplant sap and inject a toxin which breaks downtissue. Adult plant bugs are about 1⁄4 inch long,somewhat flattened and bronze in color with yel-low and black markings. They appear very earlyin spring and are present all season. Relativelyfew plant bugs can cause quite a lot of damage. Ifplant bugs have been a problem, apply anapproved insecticide just before the start of theblossom period. A second application may benecessary toward the end of bloom.

Sap beetles or picnic beetlesThese small, elongate or oval-shaped beetles are usually blackwith orange markings on theback. They readily attack dam-aged ripe fruit or overripe fruitand can be found tunneling inthe berries during harvest.

During heavy infestations, sap beetles evenattack healthy berries, especially those touchingthe soil. The problem is usually more severe insummer, and everbearing and day-neutral culti-

vars may be more heavily attacked than the ear-lier Junebearing cultivars. The beetles arestrongly attracted to areas where plant fluids arefermenting or souring. Avoid placing compostpiles near the garden, and remove all types ofoverripe or damaged fruit and vegetables. Pickberries before they become too ripe. You can trapsap beetles in cans (1-quart size) baited with amixture prepared of one cake yeast, 2 quartswater, and 5 quarts dark syrup. Place containersaround the edge of the strawberry planting, con-centrating in areas where trees border closely.

Snails and slugsSnails and slugs are neitherinsects nor the larval stagesof insects. Snails aregrayish in color,wormlike, and slimywith varying colored shells on their backs. Slugsdo not have shells, are usually mottled withshades of gray and may reach 2 inches in length.Both feed at night eating large irregular areas outof berries and foliage and leaving a glisteningtrail of slime. During the day they hide in damprefuse or under leaves or mulch. For control,apply a slug bait along the alley ways.

Spider mitesAlthough more than one speciesmay attack strawberries, thetwospotted mite is the most com-mon. Spider mites are extremelysmall, measuring about 1⁄32 of aninch. Color varies from pale yellowto red. They feed on the undersides

of leaves in a fine network of webbing. Damagedfoliage takes on a bronzed appearance and severeinfestations will destroy blossom parts.

Spider mites tend to be more of a problem duringprolonged periods of warm, dry weather. Nospecific miticides are available for control in thehome garden. However, broad-spectrum insecti-cides may help. Insecticidal soap also controlsspider mites, but it is essential to get good spray

coverage on all leaf surfaces, including theundersides. Commercially available predatorymites are a good biological control if applied earlyin a spider mite infestation.

Spittlebugs

Immature spittlebugs produce the frothy material(spittle mass) found on strawberries in May andearly June. The spittle masses contain small,bright yellow insects sucking out the plant juices.Their feeding weakens growth and stunts theberries. When the flower-bud clusters areattacked there is usually no berry production atall. Adult spittlebugs are very active throughoutthe summer, but do not cause a great deal ofdamage. Various insecticides usually provide sat-isfactory control. Each spittle mass representsonly one insect, so a few scattered masses do notjustify a spray treatment. Spittlebugs also feed onmany types of weeds, and problems may bereduced by keeping the bed and surroundingareas weed free.

Strawberry leafrollerAdult strawberry leafrollers are moths with awingspread of less than 1⁄2 inch, rusty red in colorwith brown and white markings. The moth laysher eggs near the leaf base. Eggs hatch into smallgreenish or bronze caterpillars which fold androll the leaves together while feeding. Heavyfeeding causes withering of leaves and fruits. Inaddition to conventional insecticides, microbial

FIGURE 9. Spittle masses.


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insecticides containing Bacillus thuringiensis areeffective if applied when the caterpillars are young.

Strawberry root weevilSmall brown to black weevilsappear from June through latesummer. Adult weevils feed onleaves producing small notches onthe leaf margins. Damage as aresult of adult weevil feeding isminor. However, eggs laid during

the feeding period hatch into small, white,C-shaped grubs which feed on the roots. Thegrubs completely destroy small rootlets and onoccasion feed into the plant crown. Plants wiltand die in early or midsummer. If root weevilshave been a problem, cultivate the soil and leaveit bare, free from weeds, for one year before anew planting. Adult weevils can be sprayed withinsecticides. While no chemical controls are avail-able for larvae, commercially available insect-par-asitic nematodes will control them.

Strawberry weevil (clipper)The strawberryweevil is simi-lar to butsmaller thanthe strawberryroot weevil. Adult beetlesleave their hibernation sites justbefore strawberry blossom time and move to

strawberry fields. They puncture flower budswith their mouthparts and then deposit eggs inthe punctures. After egg laying, the weevil gir-dles or clips the bud stems causing the buds todrop off or hang limp, preventing fruit forma-tion. Treat at the first sign of bud damage.

ThripsWhitened spots on the fruitsurface, golden-brownberry discoloration, or cat-facing all indicate thripsfeeding. Feeding on flowersresults in low-quality fruit.Thrips are very slender insects about 1⁄25 inchlong, usually yellowish, with wings resemblingfeathers. Generally, populations increase morerapidly during middle or late summer, makingeverbearing varieties most likely to be seriouslyaffected.

White grubsWhite grubs are generally a problem wherestrawberries are planted following sod or inweedy established strawberries. The grubs are3⁄4 to 1 inch long, white with brown heads andC-shaped bodies. Adults are the common Maybeetles or June beetles which appear in latespring and early summer. White grubs kill orweaken strawberry plants by feeding on the roots.Damage can occur for 3 years as most speciesrequire this much time to complete development.Carefully examine the soil before planting forpresence of grubs. If necessary, apply anapproved soil insecticide prior to planting. Todiscourage ongoing infestations, keep the plant-ing and surrounding areasweed free. No insecticides areregistered for use on estab-lished plantings.

FIGURE 10. Leafroller damage. Note larvaon open leaf.


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DISEASESStrawberries are susceptible to many diseases.This section describes the most common diseasesin order of importance and suggests practicesthat will help prevent and control them. Themost sensible and practical way to keep straw-berry diseases in check is by taking preventivemeasures.

You can reduce losses due to diseases by(1) using the best cultural practices, (2) selectingadapted and, if possible, resistant cultivars,(3) planting pathogen-free stock, and (4) usingthe proper fungicides as foliage sprays.

1. Cultural practices. Use the cultural prac-tices that are adapted to your area, as recom-mended elsewhere in this publication. Two essen-tial practices that aid disease control are croprotation and frequent renewal of plantings andplant stocks. Other cultural practices that helpreduce certain foliage, fruit, and crown diseaseproblems are keeping matted rows within thelimits recommended for width and plant density,and winter mulching.

Winter injury is often the cause of plant declineand death. Plant cultivars that are known to behardy in your area and protect plants with mulchin the winter.

2. Cultivars. Select cultivars adapted to yourarea. Where possible, purchase cultivars with ahigh level of disease resistance. Highly resistantplants will not become diseased; tolerant plantsmay become diseased, but their performancewon’t be significantly affected. Avoid cultivarsthat are very susceptible to one or more diseases.

3. Pathogen-free stock. Certain diseases canbe introduced into new areas by planting infectedstock. Also, other diseases will build up muchfaster when the plants that are set out are alreadyinfected. When buying planting stock, deal withnurseries that sell plants certified to be pathogen-free by their state plant-inspection service.

4. Chemical control. Accurate disease identifi-cation and proper timing of fungicide applica-tions are critical for effective disease control. Forcurrent recommendations, refer to Extensionpublication Strawberry Pest Management for HomeGardeners (A2127).

Botrytis gray moldThis disease, caused by the fungus Botrytiscinerea, is the most common and destructive dis-ease of strawberry fruit.

Symptoms. The infection often starts on blos-soms and green fruit, especially on frost-injuredflower stalks and caps, or where dead petals stickto developing fruit. Infection can prevent fruitdevelopment. Mold may also start where a berrytouches the ground, another decayed berry, or adead leaf. At first there is a light brown, soft spoton the berry. The rot spreads and usually a grayor dusty mold appears, covering the fruit. Early-season infections often show no symptoms untilafter harvest.

FIGURE 11. Botrytis gray mold.

Prevention and control. Damp, muggyweather and dense foliage shading the berriesfavor gray mold. To help prevent disease, spaceplants properly, avoid wide rows with high plantdensities, control weeds, and time nitrogen fer-tilizer and irrigation as recommended. Applynitrogen in summer and fall, not in spring. Use agood layer of mulch to protect berries from soilor decayed plants. Cultivate as little as possiblefrom bloom to harvest. During renovation,remove and destroy plant debris to eliminateoverwintering sites for the pathogen. Fungicideapplications are more effective at bloom than atharvest. The cultivars Cavendish, Earliglow,Honeoye, Jewel, Lateglow, Lester, and Tribute arehighly tolerant of botrytis.

Leaf spot and leaf scorch These infections, caused by the fungiMycosphaerella fragariae and Diplocarpon earliana,are spread by similar means and cause similartypes of damage. Therefore, prevention and con-trol measures are largely the same.

Symptoms. Leaf spot appears first as round,purple spots up to 1⁄4 inch in diameter on uppersides of leaves. Later, centers of spots become

tan, gray, or white, with the border remainingpurple. Leaf scorch produces small, dark purplespots more irregular in shape than leaf spot.They never develop light-colored centers. Spotsmay become so numerous that the leaf dries upand looks scorched.

A severe leaf spot or leaf scorch infection kills somany leaves that the whole plant is weakened orkilled. Leaf scorch can also damage berry caps,leaf stalks, runners and fruit stalks. Rain, over-head irrigation, and too much nitrogen fertilizerfavor disease.

Prevention and control.1. Renew plantings regularly—after 1 or 2 years’

cropping.

2. Use row widths of 12 to 15 inches.

3. Avoid high plant density within rows.

4. Plant resistant or tolerant cultivars. Annapolis,Crimson King, Earliglow, Glooscap, Jewel,Lateglow, Lester, Mira, and Ozark Beautyare tolerant of leaf scorch and leaf spot. Senecais tolerant of leaf spot; Redchief and Winonaare tolerant of leaf scorch.

5. Use fungicides when necessary on susceptiblecultivars.

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FIGURE 12. Leaf spot produces dark,circular spots that turn white in the center.

FIGURE 13. The irregularly shaped spotscaused by leaf scorch are uniformly dark.


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Leaf blightSymptoms. The fungus causes reddish to brownspots with purplish borders. Spots are oval to tri-angular, generally much larger than those of leafspot or leaf scorch—1⁄4 to 1 inch across. Spotscommonly extend to the margin of a leaf. Leafblight is most frequently found on mature plantsafter harvest; runner plants are seldom infected.

Prevention and control. The same chemicalcontrols used for leaf spot and leaf scorch willhelp control leaf blight. Winona appears to beresistant.

Black root rotThe black root rot complex is a general name forseveral crown and root problems that producesimilar symptoms. It is a limiting factor to grow-ing strawberries in Wisconsin.

Many factors can contribute to black root com-plex. Among them are various soil fungi and bac-teria, nematodes, winter injury, insect injury, dryweather, compacted or heavy soil, too much solu-ble salt, or high water table. Winter injury andsoil fungi appear to be the main causes inWisconsin.

Symptoms. Roots of a plant with black root rotshow one or more of the following symptoms:

1. The root system is much smaller than inhealthy plants.

2. Main roots have lesions or areas that aredarker than the rest of the root.

3. The small feeder roots are either not present orthey are dry, brittle, and dark-colored.

4. Part (usually the tips) or all of the main rootsmay be killed, and a cross-sectional examina-tion shows the dead parts to be dark in colorthroughout.

5. Cutting the crown area in half verticallyreveals discoloration and tissue breakdown.

Prevention and control. Use only plants withhealthy looking root systems and light-coloredfeeder roots. Cut through the crowns of a fewrepresentative plants and check for discolorationor breakdown of tissue. Fertilize new plantingsadequately to get good-sized, vigorous, produc-ing plants the following year. Follow carefullythe directions for applying winter mulch.

Crop rotation and the frequent renewal of plant-ings and plant stocks also help reduce chances ofroot and crown rot. Some growers plow under a

FIGURE 14. Cross-sections of a healthy root system (left) and one with winter injury, a likelycause of black root rot (right).

healthy winter injury

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planting after it has been in production for 1 year.They maintain production by setting out newplants each season. Unless plants are quite vigor-ous during the second production year, it seldompays to keep a planting for more than three pro-duction years. Winona is the only cultivar thatappears to have good tolerance to black root rot.

Verticillium wiltThis disease is caused by a soilborne fungus thatattacks the roots and vascular systems of straw-berries and other plants. The fungus is mostactive during cool weather.

Symptoms. Outer leaves wilt and dry up at themargins and between the veins; affected leaf tis-sue turns dark brown. Few, if any, new leavesdevelop. New roots that grow from the crownoften are short and have blackened tips. Severelyaffected plants collapse and die. Less severelyinfected plants are unproductive and easily winter-killed. A few plants may recover and produce anormal crop the next year. The disease oftenappears in mother plants but not in rooteddaughter plants. In new plantings, symptomsusually appear when runners begin to form. Inestablished plantings, symptoms appear aboutthe time the fruit begins to ripen.

Prevention and control. Allow at least 2 yearsafter growing tomatoes, peppers, eggplant, pota-toes, strawberries, or cane fruit before plantingstrawberries on the same land. Plant resistantvarieties such as Earliglow, Lateglow, Lester,Redchief, Settler, Tribute, or Tristar.

Leather rotThe leather rot fungus (Phytophthora cactorum) hascaused serious problems in Wisconsin. The fun-gus is soilborne and occurs naturally in manysoils. The disease tends to be sporadic, but ismost troublesome when berries are subjected toprolonged wet conditions.

Symptoms. The disease affects both green andripe berries. On green berries, diseased areas areeither dark brown or natural green outlined by

brown edging. On partly colored berries, dis-eased areas are light brown at the center andshade into purple at the edges. On fully ripeberries, there may be a slight darkening of thediseased area or no change in color. The healthyflesh of a berry that is even slightly infected withleather rot has a bitter taste.

When you cut into a diseased berry, there is noclear line separating diseased and healthy tissue.Instead, the water-conducting vessels leading toeach seed are darkened. In the final stages ofdecay, the fruit becomes tough and leathery, andoften the entire berry cluster is brown and dry.

Disease development is favored by a period ofseveral days when nighttime temperaturesremain between 55° and 65°F and moisture ispresent, followed by cloudy days with temper-atures between 65° and 80°F. Infection is alsofavored where there is little or no mulch on theground, allowing soil particles to be splashed uponto the blossoms and fruit clusters by rain andoverhead irrigation.

Prevention and control. Place up to 3 inchesof mulch on the ground between rows in thespring to prevent fruit from contacting soil eitherdirectly or by splashing water. Registered fungi-cides will provide adequate protection from thisdisease. The cultivars Lateglow and Lester areresistant to leather rot.

Red steleRed stele is caused by the soilborne fungusPhytophthora fragariae and invades the root systemof strawberry plants.

Symptoms. The plants wilt prior to and duringthe first part of the fruiting period. The centralcore (stele) of one or more of the main roots turnsreddish-brown and feeder roots are often lacking.To observe this symptom, carefully slice or splitthe roots lengthwise using a knife or razor blade,or scrape the root lengthwise several times withyour thumbnail. The dark red color may extendonly partially up several roots, or it may nearlyreach the crown area of the plant. However, red


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stele seldom invades the crown itself. The outsideof the infected roots is usually a normal, yellow-ish white color, as is the area surrounding thediscolored central core. The younger leaves takeon a bluish green cast, while the older leaves turnyellow or red.

Heavily infected plants usually die before theend of the fruiting season, while lightly infectedplants often recover during warm, summerweather as the rotted roots are replaced with newones. However, these plants seldom survive thewinter, and those that do are stunted and showtypical symptoms again the following spring. It ispractically impossible to detect and identifyinfected plants except during a 3-week periodpreceding and including the first part of the fruit-ing season.

Prevention and control. Avoid areas that haveheavy soil and are poorly drained. Do not keepplantings more than two bearing seasons; set outnew plantings where strawberries have not beengrown for 3 to 4 years. Purchase stock from nurs-eries with a good certification program. Once thesoil becomes infested, the only control is to usecultivars that are resistant to the disease. Mesabi,Mira, Tribute, Tristar, and Winona are most resist-ant, followed by Annapolis and Cavendish.Cultivars with some resistance include Earliglow,Lateglow, Lester, Redchief, and Sparkle.

Angular leaf spot Angular leaf spot, caused by the bacteriumXanthomonas fragariae, can cause serious defolia-tion of strawberry plants. It can also affect flow-ers and young berries before leaf symptomsbecome apparent. The disease is favored by cooltemperatures and high humidity.

Symptoms. The most common symptoms ofthis disease are dark green, water-soaked, angu-lar spots on the undersides of leaves. When hold-ing an infected leaf up to a bright light, the spotsappear pale green or yellow. The spots later

become visible on the upper surface as reddish orbrownish angular spots of variable sizes. Whenthe leaves are wet, bacteria ooze from the tissueas a whitish slime on the surface of the lesions.When the slime dries, it leaves a thin, clear, scalyfilm.

Prevention and control. Copper fungicidesare the only materials that might be effectiveagainst the disease. If the disease was present thepreceding year, copper sprays should be appliedas soon as new growth starts in the spring.Several additional applications at 7- to 14-dayintervals may be needed. Never exceed the raterecommended on the product label becauseexcessive copper is toxic to plants. Also, do notspray copper when temperatures are above 80° to85°F as plants may be injured. No cultivars areresistant, but Honeoye is noticeably susceptible.

Viruses and phytoplasmasMost strawberry diseases caused by viruses arisefrom two or more viruses in the same plant (avirus complex). Often, the plants do not showobvious disease symptoms. However, the infec-tion weakens the plant, reducing berry produc-tion and quality.

The disease aster yellows was once thought to bea viral infection. It is now known to be caused bya phytoplasma found in plant phloem cells. Thepathogen is carried and spread by the feeding ofthe six-spotted aster leafhoppers. Plant symptomsare much like severe 2,4-D herbicide injury, withyellowing, dwarfing, and cupping of youngleaves. Abnormal green, leafy flowers are oftenproduced, resulting in little or no berry production.

A disease called “multiplier” is also caused by aphytoplasma. Affected plants are small andspindly and have many crowns, sometimes asmany as a hundred. Leaves are one-third to one-half normal size, leaf stalks are short, and thereare only a few short runners.

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Prevention and control. Most viruses andphytoplasmas are spread from plant to plant bythe feeding of insects, particularly aphids andleafhoppers. To reduce the spread of these dis-eases, apply a recommended insecticide through-out the first growing season and up until bloom,and then after the fruiting period during thebearing year.

When setting out a new planting, always useplants that are certified to be virus-tested. Virus-tested plants of most cultivars are now availablefrom reliable nurseries.

NematodesNematodes are tiny, threadlike worms that aretoo small to be seen easily by the unaided eye.Most nematodes in a typical soil are harmless toplants. Those that cause injury to plants by feed-ing on or invading the root system are calledplant parasitic nematodes.

Nematodes are of minor importance on strawber-ries in Wisconsin, probably due to our cold win-ters. Occasionally, northern root knot nematodesinfect plants in a few restricted areas in a plant-ing. This nematode forms swellings or galls onroots. The galls range in size from a mere speckto 1⁄4 inch in diameter and interfere with the nor-mal functioning of the roots.

Root lesion, dagger, and sting nematodes areoccasionally found in soils where strawberriesare grown, but they seldom cause sufficientinjury to the plants to warrant control measures.

PROBLEM SOLVING

Why plants fail to bearThere are many reasons why strawberries don’tbear fruit—spring frosts, too much fertilizer,weed competition, or pests. This sectiondescribes the most common problems and howto avoid them.

Cold injury. Strawberries are susceptible to win-ter cold injury. Plant injury begins when thecrown temperature (not air temperature) reaches23°F. The amount of damage increases as thetemperature drops below 23°F, with substantialinjury or plant death occurring at 4°F. Mulchinghelps keep the crown temperatures stable.Suitable mulching materials will trap air andmaintain loft throughout the winter. In areaswhere snow cover is deep and reliable, mulchingis not necessary for protection. Ice over themulch reduces loft and conducts heat from theplants. Ice should be avoided.

Spring frosts. Spring frosts pose perhaps thelargest risk to successful strawberry production.When air temperatures at canopy height dropbelow 28°F injury will occur. To avoid damage,protect plants and blossoms when frosts are fore-casted. Small plantings can be covered withstraw, tarps, or row covers that will trap the heataround the plants. Covers should be put in placeshortly after sundown and should remain on theplants only until the air temperature is abovefreezing in the morning.

Overfertilization. When bearing plantingsreceive heavy nitrogen applications before har-vest, the plants produce vegetative growth at theexpense of fruit growth. Strawberries requiremoderate nitrogen fertilization. Bearing plantingsshould only receive nitrogen after harvest. Youngplantings should be well fertilized to encouragerunnering.

Overcrowding. Most strawberries are producedat the row edges. When strawberry patchesbecome a solid mat rather than a collection ofrows, yields and fruit quality decline. Don’tallow matted beds to be wider than 12 to15 inches to maximize the linear feet of row edge.

Weeds. Strawberries do not compete well withweeds. Weeds will shade strawberry plants andcompete for water and nutrients. Grass weedsare most competitive. Weedy berry patches willproduce few fruit of poor quality.


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Insects. Clipper weevils can devastate straw-berry plantings. If not controlled, clipper weevilswill clip the stem of virtually every flower,destroying fruit production.

Poor fruit qualityIn some instances strawberry plantings producefruit, but the fruit are small, poorly colored andof low quality. This section describes severalproblems that lead to poor fruit quality.

Age. As plantings age yields decline. Strawberryplantings are usually kept to bear fruit between 3and 5 years. After that the planting should beremoved and another crop rotated into that spacefor a year or two before replanting. Old plantingsusually have more weed and insect pests thanyounger plantings.

Neglected plantings. Fruit quality sufferswhen plantings are not cared for. The plants needto be cultivated, fertilized, and have pests con-trolled as described in this bulletin. Reclaimingneglected plantings is usually not effective. It isbetter to remove the planting and start over.

Poor growing conditions. Patches establishedin poor sites will produce poor fruit. Wet, shady,or droughty sites will result in poor plant growthand few small fruit. The soil should also be pre-pared properly before planting. Adding organicmatter to soils before planting will improve soilcharacteristics.

Insect and disease pests. The most commoninsect pest of strawberries is the tarnished plantbug. Tarnished plant bug injury results in mis-shapen, seedy fruit. Gray mold and leather rotare the most important disease problems. Plantsinfected with gray mold will have gray to whitefuzzy growth on ripe fruit. Berries with leatherrot will have discolored spots and a bitter flavor.See the insect and disease sections for more infor-mation on managing these pests.

Inferior cultivars. Inferior cultivars will pro-duce inferior fruit. For the best chance of successplant cultivars recommended in this bulletin,Home Fruit Cultivars for Northern Wisconsin(A2488), or Home Fruit Cultivars for SouthernWisconsin (A2582).

Why plantings failPlant death is usually caused by a number ofinteracting factors rather than by a single identifi-able cause. One injury may provide sufficientstress to allow other problems to eventually killthe plants. Several reasons for plant death aredescribed here.

Winter injury. Strawberry plants are quite win-ter tender and require protection during the win-ter to survive and produce fruit. Strawberryplantings are usually covered with 2 to 4 inchesof a loose mulch such as straw or chopped cornstalks. Covering plants with mulch too early inthe fall will not allow them to harden off suffi-

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ciently for winter. Removing the mulch too earlyin the spring may subject the plants to frosts. Onthe other hand, removing the mulch too late willreduce yields. Snow can be captured over straw-berry plants during the winter by placing snowfencing to the windward side of the plants.

Too much water. Strawberry plants will nottolerate wet feet. Saturated soils do not allow airto reach the roots and they predispose the rootsto root diseases such as red stele. Plant strawber-ries only in well-drained soils. Irrigate prudentlyso soils don’t remain wet.

Drought. Strawberry plants have shallow rootsthat don’t explore a large volume of soil. Whensoils are allowed to become too dry the plantswill die. Weeds will also compete with straw-berry plants for moisture when water is in shortsupply. Light sandy soils are particularly prone todrought. Adding organic matter, controllingweeds, and irrigating will keep soils moist.

Mechanical injury. Physical damage to straw-berry plants can be caused by a variety ofsources, including lack of care while picking, set-ting mowers too low at renovation, and deer andother animals browsing. Fencing the berry patchwith chicken wire will help keep small animalsfrom the patch. There is little that can be done tokeep large animals out of the patch. Use care atrenovation to keep from injuring the crowns. Ifthe crowns are damaged, the plants are unlikelyto survive.

Insect and disease pests. Severe infestationsof insects or diseases can weaken plants makingthem prone to winter injury or summer droughts.While these pests seldom kill plants outright,they are often contributing factors. Manage insectand disease pests using the practices describedearlier in this publication.

RELATED PUBLICATIONS

For home gardeners

Fertilizing Small Fruits in the Home Garden(A2307)

Home Fruit Cultivars for Southern Wisconsin(A2488)

Home Fruit Cultivars for Northern Wisconsin(A2582)

Strawberry Disorders: ■ Black Root Rot (A3231)■ Strawberry Gray Mold (A3232)■ Leaf Spot and Leaf Scorch (A3233)

Strawberry Pest Management for HomeGardeners (A2127)

For commercial growersCompendium of Strawberry Diseases, APS Press,(800) 328-7560

Midwest Small Fruit Pest ManagementHandbook (Bulletin 861), Ohio State University,(614) 292-1607

Strawberry and Raspberry Pest Management inWisconsin (A1934)

Strawberry Production Guide for the Northeast,Midwest, and Eastern Canada (NRAES-88),Cornell University, (607) 255-7654


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This list of nurseries is provided as a convenience for our readers. It is not an endorsement byExtension, nor is it exhaustive. The plant materials listed in this bulletin may be available from otherequally suitable nurseries.

N URSERIES

Brittingham Plant FarmsP.O. Box 2538Salisbury, MD 21802(410) 749-5153

Farmer Seed & NurseryP.O. Box 129Faribault, MN 55021(507) 334-1623

Hartmann’s Plantation, Inc.310 60th StreetGrand Junction, MI 49056(616) 253-4281

Henry Field’s Seed & Nursery415 North BurnettShenandoah, IA 51602(605) 665-9391www.henryfields.com

Indiana Berry & Plant Co.5218 W 500Huntingburg, IN 47542(800) 295-2226

J.W. Jung Seed335 South High StreetRandolph, WI 53957(800) 247-5864www.jungseed.com

Keddy’s Nursery982 North Bishop RoadKentville, Nova ScotiaCanada B4N 3V7(902) 678-4497

Makielski Berry Farm & Nursery7130 Platt RoadYpsilanti, MI 48197(313) 434-3673

Mellinger’s, Inc.2310 W. South Range RoadNorth Lima, OH 44452(800) 321-7444www.mellingers.com

Miller Nurseries, Inc.5060 West Lake RoadCanadaigua, NY 14424(800) 828-9630www.millernurseries.com

Nourse Farms, Inc.RFD, Box 485South Deerfield, MA 01373(413) 665-2658www.noursefarms.com

Peaceful Valley Farm SupplyP.O. Box 2209Grass Valley, CA 95945(530) 272-4769www.groworganic.com

Stark Brothers Nurseries & Orchards Co.Highway 54 WestLouisiana, MO 63353-0010(800) 325-4180

Swedberg NurseriesHighway 210 WestBattle Lake, MN 56515(218) 864-5526

Copyright © 1999 by the Board of Regents of the University of Wisconsin System doing business as thedivision of Cooperative Extension of the University of Wisconsin-Extension. Send inquiries about copyrightpermission to: Director, Cooperative Extension Publishing, 201 Hiram Smith Hall, 1545 Observatory Dr.,Madison, WI 53706.

Authors: B.R. Smith is professor of horticulture, College of Agriculture, Food, and Environmental Sciences,University of Wisconsin-River Falls. D.L. Mahr is professor of entomology, P.S. McManus is assistant profes-sor of plant pathology, and T.R. Roper is associate professor of horticulture, College of Agricultural and LifeSciences, University of Wisconsin-Madison and University of Wisconsin-Extension, Cooperative Extension.Produced by Cooperative Extension Publishing. Cover illustration by Catherine Baer, copyright 1999.

University of Wisconsin-Extension, Cooperative Extension, in cooperation with the U.S.Department of Agriculture and Wisconsin counties, publishes this information to further the purpose of theMay 8 and June 30, 1914 Acts of Congress; and provides equal opportunities and affirmative action inemployment and programming. If you need this material in an alternative format, contact the Office ofEqual Opportunity and Diversity Programs or call Cooperative Extension Publishing at (608) 262-2655.

This publication is available from your Wisconsin county Extension office or from CooperativeExtension Publishing, Rm. 170, 630 W. Mifflin St., Madison, Wisconsin 53703. Phone (608) 262-3346 or calltoll free (877) WIS-PUBS (947-7827). Web address: http://www.uwex.edu/ces/pubs/. Before publicizing,please call for publication availability.

A1597 GROWING STRAWBERRIES IN WISCONSIN R-04-99-5M-400

growing strawberries in wisconsin

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