kentucky pest news, april 16, 2013

7/28/2019 Kentucky Pest News, April 16, 2013

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Online at: www.uky.edu/KPN

Number 1335 April 16, 2013

AGRONOMIC CROPS- Early Season Vegetable Insect Management

GRAIN CROPS-Armyworm Flight Begins

TOBACCO- Disease Update for the Week of April 15, 2013

TURF- Ground Nesting Bees

PEST OF HUMANS-Lone Star Ticks Active

INSECT TRAP COUNTS

AGRONOMIC CROPS

Early Season Vegetable Insect ManagementBy Ric Bessin, Entomologist

Early in the season it is important to get thevegetable seedlings and transplants off to a goodstart. It’s been a more delayed spring this year andmany growers may feel rushed to get plants intothe field as fast as possible, but we shouldn’tforget about early season pests in our haste. Thereare a few early season insects that need to bemanaged to ensure plant establishment and healthystands.

Cole crops (Cabbage, Broccoli, Cauliflower)Striped flea beetles, imported cabbageworm anddiamondback moth larvae are the pests that attackthe spring crop. With flea beetles on seedlingplants, less than 4 to 5 true leaves, use a thresholdof an average of two beetles per plant whendeciding whether or not to spray. A threshold of 15 percent infested plants can be used with wormsuntil either head-fill or crown formation, then thethreshold drops to 5 percent infested plants. Whilethe type of mixture of worms it is not importantwhen deciding if to spray, the types of worms willdetermine which insecticides are used. Cabbageaphids are also common in cool weather.

Figure 1. Cabbage aphids on cabbage.

Sweet CornCorn flea beetles and cutworms are the twoprimary pests that will attack seedling corn. Use 3percent cut plants with cutworms actively feedingas the guideline for treating cutworms. Flea beetlescan transmit the bacterium that causes Stewart’sWilt, so wilt-resistant cultivars may be needed inyears following mild winters. Otherwise thethreshold for direct feeding by corn flea beetles is50 percent of the plants with leaf scars and some

leaves turning white. We have also been seeingincreasing armyworm flights this spring.

Lexington, KY 40546

http://www.uky.edu/KPN






Figure 2. Black cutworm and corn. Tomatoes and Peppers Tobacco and potato flea beetles will attack bothtomato and pepper plants. Usually, the plants willquickly outgrow moderate damage. Occasionally,

serious damage can occur to plants less than sixinches. Use 4 or more beetles per plant and plantsless than 6 inches as the guideline for treatment.Colorado potato beetle can also do serious damageto tomato plants less than 8 inches. Use 10 beetlesper 20 plants as the guideline for treatment whenthe plants are less than 8 inches. In counties wherebrown marmorated stink bug has been established,growers should be on the lookout for this new pestas the plants begin to fruit.

Figure 3. Flea beetle damage to tomato. Eggplant and PotatoAs with tomato, flea beetles and Colorado potatobeetle are serious early season pests of potato andeggplant. Use the same threshold for tomatoesabove. Resistance to insecticides continues to be aserious problem for Colorado potato beetle.Because of this, producers should not useinsecticides with the same mode of action for

consecutive generations of this insect. Often localpopulations of this insect may be resistant to onegroup of insecticides, and in other areas they maybe resistant to others. For this reason, what workswell in one county may not work at all in another.

Figure 4. Colorado potato beetle. Squashes, Cucumbers and MelonsStriped and spotted cucumber beetles can attackcucurbit crops anytime after seedling ortransplanting. Cucumber beetles also transmit thebacterium that causes bacterial wilt. For thisreason, cucurbit crops must be treated forcucumber beetles as soon as they are planted. Withbacterial wilt susceptible crops, cucumber beetlesneed to be effectively controlled through the startof flowering. Keep in mind that cucurbits areinsect-pollinated, so measures need to be taken tocontrol the beetles and avoid hurting pollinators.One method to avoid injuring pollinators duringbloom is to spray in the early evening afterpollinators have quit. The squash and pumpkinflowers that are open will be closed the next dayand new blooms free of insecticide on the innersurface will be open the following day.

Figure 5. Sqauah bug adults and nymphs.



The other pest of cucurbits is the squash bug.Squash bugs attack cucurbits in early June andfeed with piercing sucking mouth parts. They aremost commonly found on squashes and pumpkin,but will feed on other cucurbits. They transmit thebacteria that cause yellow vine decline which can

be a serious disease of pumpkin, some squashes,and watermelon. The key to controlling thedisease is to control this insect pest.

Drenches of Admire, Belay or Platinum are usedto control cucumber beetles and also help tosuppress squash bug. However, theseneonicotinoid insecticides are under fire in themedia due to reported ties to honey bee losses.

This controversy is active and more studies willshed light on this in the future. What is importantis for growers to follow the label instructions

carefully and provide as much time as possiblebetween soil applications and the onset of flowering.

GRAIN CROPS

Armyworm Flight BeginsDoug Johnson, Extension Entomologist

Figure 6. Armyworm moth (Adult)

Spring must really be here as armyworm (aka truearmyworm) moths have taken flight. Only a fewmoths have been captured thus far, but it doessignal the beginning of insect season in the fieldcrops and the current year’s capture is in line withthe outbreak year of 2008. It is still too early to getreal excited but important enough to be aware.

In Kentucky, armyworm can be an important pestof corn and wheat. Corn products that contain a Bt

trait that provides protection from caterpillarfeeding (See: Insecticide recommendations forcorn: http://pest.ca.uky.edu/EXT/Recs/ENT16-Field%20corn.pdf , pages 6-7) will likely beprotected. However, non-Bt types including fieldcorn refuge, popcorn, food-grade corns, and

sweetcorn along with wheat will be at risk.

We are several weeks from any damage caused byarmyworm as the adult moth is not the damagingstage. Monitoring this stage just gives us a“biofix” or heads-up that the pest is about. It is thecaterpillar in which we are interested. You maywant to check the flight graphs each week for theprogress in this population. These may be foundat: http://www.uky.edu/Ag/IPM/ipm.htm. It onlytakes a few seconds to check and this can give youan idea of the relative risk of this pest for this

season. On the graph you can see displayed thecurrent year’s capture (green), the rolling five-year average (blue), and known populations thathave resulted in outbreaks (red and/orblack) Thiswill give you a rough estimate of the currentyear’s relative risk. As these graphs representmoth flight, the relative population size can beseen before the damaging stage, the caterpillar,develops.

If populations appear to be indicating an elevatedrisk, I will use a temperature-based model to

predict when the caterpillar stage will appear. Thismodel will NOT predict which fields will beinfested. One must scout fields to know if thearmyworm is present, but the model will providean estimate of when the field should be scouted.Remember, the model predictions will be based onthe capture and temperatures at the UK-REC inPrinceton (Caldwell Co.) KY. In areas to the southand southwest of the UK-REC caterpillardevelopment will be ahead and areas to the northand northeast of the UK-REC will be a bit behind.I will post, and you may review, the results of

these model runs each week in this publication.So, if you are the pest manager for wheat or cornthis spring, keep yourself tuned to this outlet for“Early Warnings” about this pest.

http://pest.ca.uky.edu/EXT/Recs/ENT16-Field%20corn.pdf



http://www.uky.edu/Ag/IPM/ipm.htm







TOBACCO

Disease Update for the Week of April 15, 2013 By Kenny Seebold, Extension Plant Pathologist

Tobacco transplant production has gotten off to a

bit of a slow start in Kentucky, due to coolconditions. However, weather patterns over thepast couple of weeks have warmed things up a bit,and have also created disease-favorable conditionsin float beds around the state. We’ve recentlyfound Rhizoctonia damping-off, Pythium root rot,and Sclerotinia collar rot. If producers haven’talready started a fungicide program, now is thetime to begin (see KPN No. 1333; April 2, 2013for an example of a recommended spray schedulefor tobacco transplants). For recommendedmanagement practices, consult previous issues of

Kentucky Pest News for articles on managingPythium root rot, Rhizoctonia damping-off, andtarget spot (No. 1331; March 12, 2013).Identification and management of Sclerotiniacollar rot is the focus for this week’s article.

BACKGROUND. Collar rot normally appears infloat beds around mid-to-late April, and afterclipping has begun. Resting structures (sclerotia)of the collar rot pathogen, normally locatedoutside the float system, come out of their dormantstate and produce cup-shaped fruiting bodies

called apothecia. Apothecia then produce spores(ascospores) that are dispersed on wind currents.When ascospores land on susceptible tissue, theygerminate if sufficient moisture is present. Longperiods of leaf wetness (greater than 16 hours) arerequired for this process. Germinated ascosporesproduce hyphae (fungal “threads”) that penetratetissue and begin the infection process.

SYMPTOMS. The first symptoms of collar rotare small, dark green, water-soaked lesions thatappear at the bases of stems; however, these

symptoms are not seen commonly. In most cases,this disease becomes apparent when cankers onlower stems result in chlorosis of older leaves andsubsequent wilting of plants or flagging of leaf tips(Fig. 7). When clusters of infected transplantscollapse, open holes are formed in the plantcanopy (Fig. 8). These clusters, or “foci”, areusually grapefruit-sized (4-6” in diameter). Stemsof affected seedlings generally show a wet

necrosis that is amber-to-brown in color,beginning at the base of the plant and extendingupward (Fig. 9). Signs of the causal agent,Sclerotinia sclerotiorum, may be present onsymptomatic plants or on debris in float trays.

These signs include a white, cottony mycelium

(fungal mass), present if humidity is high, andirregularly shaped, sclerotia that are white at firstand turn black as they mature (Fig. 10). Sclerotiaresemble seeds or rodent droppings and are theprimary survival structure of S. sclerotiorumandare the primary source of inoculum for outbreaksin subsequent years.

Plants that are 5-7 weeks old are most susceptibleto collar rot. We often see the first cases shortlyafter plants are first clipped following a period of disease-favorable weather. Cool temperatures (60

to 75 ºF), high humidity, and overcast conditions,like those that have been common in Kentucky forthe past week, are ideal for development of thisdisease. It’s also important to note thatS.sclerotiorumis an efficient colonizer of dead plantmatter and weakened or injured tissue, and theseare usually the first to be attacked. The funguswill then move from these areas to nearby healthyplants as long as cool temperatures and highhumidity prevail. This is one of the ways thatsecondary spread of the collar rot pathogen takesplace, sinceS. sclerotiorumdoes not produce

airborne spores on infected tissue. The other wayin which secondary spread can occur is throughdispersal of infected tissue, which happens wheninfected plants are clipped.

MANAGEMENT. There are no fungicideslabeled specifically for control of Sclerotinia collarrot on tobacco transplants, making this a difficultdisease to manage. Sound management practicesare the most important options that a grower canuse to fight collar rot. Adequate ventilation andair circulation are primary concerns, since these

limit the duration of leaf and stem wetness.Growers should manage temperatures to promotehealthy plants and minimize injury. The latter isimportant because injured tissues are moresusceptible toS. sclerotiorum. Fertility should bekept at around 100 ppm (N); excessive levels of Ncan lead to a lush, dense canopy that will takelonger to dry and will be more susceptible toattack by the collar rot pathogen. Leaf clippings



should not be allowed to build up in transplanttrays or remain in contact with seedlings. Mowseedlings at a low engine speed with a well-sharpened blade to ensure complete removal (andcapture) of leaf pieces in the least injurious waypossible. Frequent clippings will reduce the

amount of tissue that must be removed by themower and will cause less plant injury. Theseresult in less leaf material left on the surface of thetransplant trays. The collar rot pathogen canoverwinter on clippings and diseased plants, sothese should be discarded a minimum of 100 yardsfrom the transplant facility, or buried, to reducethe chance of spores making their way back intonearby float beds. Home gardens should not beplanted near transplant facilities, and keep a weed-free zone around float beds. Over 300 species of plants, including many weeds, are hosts toS.

sclerotiorum, making many weeds potential hostsfor this pathogen.

Figure 7. Early symptoms of collar rot include yellowing of

leaf tips and flagging of older leaves.

Figure 8. Collapse of clusters of plants leaves softball- to

grapefruit-sized openings in the plant canopy.

Figure 9. Stems infected by S. sclerotiorum typically are

water-soaked and exhibit a dark-brown necrosis.

Figure 10. Signs of the collar rot pathogen include dense,

white fungal growth and black, irregular sclerotia ranging

from the size of a mustard seed to a raisin.

TURF

Ground Nesting BeesBy Lee Townsend, Entomologist

Figure 11. Common ground nesting bees



Ground-nesting bees include several species of 3/8” to ¾” long hairy insects with solid black tometallic green or dark bodies. These importantwild pollinators become active in the spring,digging pencil-diameter tunnel openings in theground. The holes usually are surrounded by fine

soil particles that the bees kick out as they dig.Usually, their activity ends by mid-summer andthe holes close.


Ground bees burrow in well-drained soils in sunnyopen areas near flowering trees. They collectnectar and pollen which is carried back to theburrow to serve as food for their developing grub-like larvae. Females will dig and stock severalunderground burrows, sealing them off as each is

stocked with food and receives an egg. Thedeveloping bee spends the summer and winter inthe soil and emerges as an adult in the followingspring Often, there is only one generation eachyear. Over time, large bee communities candevelop where soil conditions are favorable andflowers are abundant.


Ground bees can sting if handled or mashed butare not aggressive and do not defend their nest

area like honey bees or ground-nesting wasps do.If practical, ground bees should be left alone to dotheir valuable work. Nesting areas can be mowedat night when the bees are not active.

PESTS OF HUMANS

Lone star ticks activeBy Lee Townsend, Extension Entomologist

Figure 14. Underside view of a lone start tick nymph.

The first lone star tick of the season came in fromLincoln County last week. They are easilyrecognized by their long mouthparts. Nymphs (animmature stage) and adults have 8 legs. Seed tickshave only six.

Nymphs and adults begin to seek hosts in lateMarch or early April and can be found into July.

The tiny seed ticks (also called turkey mites) aremost abundant from late July through September.

This tick is abundant in western and south centralKentucky and parts of eastern Kentucky. It is lesscommon in the Bluegrass and north central part of the start. The American dog tick will be activesoon across the state, as well.

The lone star tick is not a vector of Lyme diseasebut is associated with Southern Tick-borne RashIllness (STARI), human erlichiosis; severe allergicreaction occur in some individuals in response tomultiple bites. All three stages can feed on smallor large mammals and ground-nesting birds. Moreinformation is available in this publication:http://www.ca.uky.edu/entomology/entfacts/ef648.asp.

http://www.ca.uky.edu/entomology/entfacts/ef648.asp







Tick numbers tend to be high in around clearingsand along so be especially careful in these areas.Here are some tips to protect you from ticks:■ Wear light-colored clothing so ticks can be seeneasily■ Tuck pants into socks and shirt into pants keep

ticks from reaching your skin – a band of duct tape(sticky side out) around the lower legs will help totrap ticks that have latched on as you passed by.■ Avoid or minimize time in tick habitats■ Use personal protection - repellents (DEET orpicaridin) or permethrin-based (Permanone)clothing sprays■ Inspect your clothing and body regularly andremove ticks, especially at the end of the day.

Ticks wander on the body for some time beforesettling to feed. Often, they can be found beforethey become attached.

■ Take a warm soapy shower after potential tickexposure■ Wash clothing in hot water and detergent - storein sealed bag until it is washed

Removing TicksBarbed mouthparts and cement secreted as theyfeed cause ticks to be anchored firmly to the skin.Use fine-tipped tweezers to grasp the tick as closeto the skin surface as possible. Then, pull upwardwith steady, even pressure. The longer the tick hasbeen in place, the harder it is to remove. Twisting

or “unscrewing” the tick may cause themouthparts to break off and remain in the skin.After removing the tick, thoroughly disinfect thebite site and wash your hands with soap and water.

2013 INSECT TRAP COUNTS

April 5- 11

Graphs of insect trap counts for the 2013 seasonwill available soon on the IPM web site at -http://www.uky.edu/Ag/IPM/ipm.htm.

Note: Trade names are used to simplify the informationpresented in this newsletter. No endorsement by theCooperative Extension Service is intended, nor iscriticismimplied of similar products that are notnamed.

Location Princeton,KY

Lexington,KY

Black cutworm 9 16Armyworm 136 72European CornBorer

0 0

Corn earworm 0 0

kentucky pest news, april 16, 2013

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