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In This IssueCrop ConditionsIndiana Climate and Weather ReportRootstocks, Replant, and ReconsiderationsSixth annual Great Lakes Great AppleCrunchLafayette-area corn maze themed forPurdue’s ‘Giant Leaps’ wins USA TodaycontestHLA Extension Events

Crop Conditions(Peter M Hirst, hirst@purdue.edu, (765) 494-1323) & (BruceBordelon, bordelon@purdue.edu, (765) 494-8212)

Blackberry- harvest continues

PawPaw- harvest continues

Raspberry- harvest continues

Grape- harvest underway

Apple- harvest underway

Indiana Climate and WeatherReport(Beth Hall, hall556@purdue.edu)

The initial cool wave of September is likely overas we welcome warmer temperatures for thenext several weeks. The Climate Prediction

Issue: 19-12September 12, 2019

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Center is showing strong confidence for above-normal temperatures through September 24rd,which should help accumulate growing degreedays and move agricultural production furtheralong.

Outlooks are showing significant probabilities forabove-normal precipitation over the next fewweeks, but it is uncertain how much and whenthat precipitation will occur. The 3-month(September-November) climate outlook isindicating significant probabilities for above-normal temperatures.

This will hopefully discourage any cold wavespassing through from causing an earlier-than-desired hard freeze event. However, keep inmind that predictions are still too far in the futureto provide any certainty and climate outlooks areunable to account for a brief (1-to-3-day) eventfrom passing through with temperatures lowenough to cause a frost. Primary message: stilltoo soon to predict when the first fall frost willoccur.Beth Hall, PhDDirector, Indiana State Climate Office

Rootstocks, Replant, andReconsiderations(Janna L Beckerman, jbeckerm@purdue.edu, (765)494-4628)

Rootstocks, Replant, and ReconsiderationsReplant disease is a term that describes reducedproductivity and ‘failure to thrive’ of newplantings of trees back into orchards of the sameor closely related tree fruit (or nut) crops.Historically, it has been referred to as ‘soilsickness, soil exhaustion, replant disorder, andreplant problem’. Regardless of name, replantdisease is a complex interaction of abiotic factors

(loss of soil fertility, residual herbicides, otherresidual pesticides), fungal pathogens likeRhizoctonia and Cylindrocarpon, along with theoomycetes Pythium spp. and Phytophthora spp.along with the nematodes like Pratylenchuspenetrans (Fig. 1).

Figure 1 Apple replant disease cycle. Illustration credit:Indika Ratnayake from

http://treefruit.wsu.edu/crop-protection/disease-management/apple-replant-disease

Rootstock selection literally and figuratively setsthe foundation for grower viability and success,and is just as important as the choice of fruitingcultivar. Rootstocks impact disease resistance(and pesticide inputs), fruit size and yield, treevigor (including precocity and productivity), andwinter hardiness. This is the type of long-termresearch that both the Land Grant University andUSDA-ARS were created for, to improve thehealth of orchard systems, and the sustainabilityof tree fruit production.From this collaboration, several new rootstockswere selected, bred, and developed. Of these, G.935 is considered to be “a very reliable, replant-tolerant rootstock.” Although lacking in woollyaphid resistance, it’s posited as a heavy cropperwith good winter hardiness in a tree with size andvigor somewhere between M.26 and M.9. Thereare replicated trials and data to support thesecontentions (Russo et al. 2007), and ‘resultsdemonstrate the ability of new rootstock clonesto perform better than current commercialstandards, reducing financial risk to producerswhile promoting orchard health with enhanced

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disease resistance.’Unfortunately, around 2015 (Auvil,201X) growerswere warned that “high yields from theserootstocks can cause the scion to slide off therootstock, especially when the trellis fails.” In2018, we planted Rosalee with a vertical, 3-wiretrellis. To date, we’ve lost…, and continue to losedespite increasing the trellis lines to 4. Obviously,slipping from the rootstock doesn’t reducegrower financial risk! It also doesn’t explain ourexperience with this rootstock and the cultivar‘Rosalee’, which is sliding off the rootstock evenwithout fruit on the tree. So, what is going on?Why is the published data so different from ourreality? And what is a grower to do?To begin with, I think we need to recognize thatit’s much easier to get a result than an answer.The results published in 2007 were just one ofmany temporary truths, which is why agriculturalscientists repeat experiments in differentlocations, and with different combinations (in thiscase, site, scion, rootstock, time). These differentsituations result in outcomes that are subject tochange when the new data is added to previousinformation. In this way, I think we can identifyand acknowledge a problem with science: In thebeginning of any study, there is a lot ofuncertainty. It takes very little data to yield alarge reduction in that uncertainty. In this case,the 2007 article reported experiments thatinvolved three rootstocks and scion combinationsin two sites and yielded a data that suggestedthat these rootstocks were better than B.9 and M.26. There have been other rootstock trials acrossthe country (you can read about the NC-140Regional Rootstock Research Project athttp://www.nc140.org/plantings.html ). Many butnot all of these studies showed improvedoutcomes with the new rootstocks. However, asstudies continued, not everyone saw the sameresults. Unfortunately, these subsequent studies

never get the coverage of the first studies (whichis true about everything!).Worse still, many growers are getting results thatconflict with previous answers, and losing moneyin the process. So, the choice facing growersregarding which rootstock to use comes down torisk. Risk is simply defined as the uncertaintyabout the outcome, in this case, using a newrootstock on their site. Although an increasingamount of data is available (with noisy,conflicting results!), it isn’t available for yourspecific site, nor was it available for our scion-rootstock combination. For this reason, Irecommend caution when using choosing newrootstocks, as your mileage may vary, and themore uncertainty (risk) you have about theoutcome. Start small before investing inhundreds of rootstock scion combinations youhaven’t tested at your site so you don’t losethousands of trees (Courtney, 2017).As for our block of Rosalee/G.935, the reasons forour rootstock failures are not clear, althougheveryone seems to have hypotheses regardingwhy. Few people (including me!) have data tosupport their claims. At this point, I feel safe insaying the incredibly obvious: Certaincombinations of scion and G.935 (or G. 41) areprone to failure, and these include Rosalee andRoyal Red Honeycrisp. Until more is known,growers should only use known combinations(like Gala and Fuji) with G. 935, and implementand maintain a trellis system when plantingthem. When considering new combinations, do asmall-scale test to see how the combinationperforms at your location.Hopefully, no one is swearing at the scientistsand their statistics. It’s important to rememberthat it’s easier to lie without statistics than it is tolie with them. Data and the appropriate statisticsprovide and enforce boundaries. Unfortunately,people (including scientists) like to extrapolate

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from the data they have, despite the boundariesthat data provides. What we’ve learned is that “Itis better to take many small steps in the rightdirection than to make a great leap forward onlyto stumble backward.”

All trees showed a similar pattern of breakagebetween the G. 935 rootstock and Rosalee scion.

Losses continue in year 2 and increasing trellislines from three to four.

Auvil, T. 2017. Geneva Rootstock Performance:2016 Rootstock Trial Update. Available online at:http://treefruit.wsu.edu/article/geneva-rootstock-performance-2016-rootstock-trial-update/ Lastaccessed 9/3/2019.Courtney, R. 2017. Problematic pairings withGeneva 935. The Good Fruit Grower. January 1st2017 Issue. Available at:https://www.goodfruit.com/problematic-pairings-with-geneva-935/Hewavitharana, S. et al. 201X. Apple ReplantDisease. Available online at:http://treefruit.wsu.edu/crop-protection/disease-management/apple-replant-disease/. Lastaccessed 9/3/2019.Mazzola, M. 1997. Identification andpathogenicity of Rhizoctonia spp. isolated fromapple roots and orchard soils. Phytopathology

87:582-587.Mazzola, M., and Brown, J. 2010. Efficacy ofbrassicaceous seed meal formulations for thecontrol of apple replant disease in conventionaland organic production systems. Plant Dis.94:835-842.Russo, N., Robinson, T., Fazio, G. and Aldwinckle,H. 2007. Field evaluation of 64 apple rootstocksfor orchard performance and fire blightresistance. HortScience 42:1517- 1525.

Sixth annual Great LakesGreat Apple Crunch(Peter M Hirst, hirst@purdue.edu, (765) 494-1323)

Join participants across Indiana, and the greater-Midwest on Thursday, October 10, 2019, for thesixth annual Great Lakes Great Apple Crunch! Or,host your Crunch any day and time in Octoberthat works for you. Register below to receive the2019 Apple Crunch Guide and stickers! The GreatLakes Great Apple Crunch is a great way forschools, early care sites, business campuses,hospitals, farmers and others to celebrate localfarmers and purchase Indiana-grown apples!Participants of all ages and at all organizationsare invited to help us reach our goal of 1.7MILLION CRUNCHES this year!https://www.cias.wisc.edu/applecrunch/

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Lafayette-area corn mazethemed for Purdue’s ‘GiantLeaps’ wins USA Todaycontest(Peter M Hirst, hirst@purdue.edu, (765) 494-1323)

Get the story here!Lafayette-area corn maze themed for Purdue’s‘Giant Leaps’ wins USA Today contest

HLA Extension Events(Lori K Jolly-Brown, ljollybr@purdue.edu)

September 5, 2019 Hydroponics & GreenhouseworkshopPurdue University, Deans auditorium, HLAgreenhouseContact Lori Jolly-Brown, ljollybr@purdue.eduParticipants learned about optimal conditions forgrowing hydroponic lettuce, including nutrientrecipes, production systems, artificial lightingpractices and optimal temperatures for lettuce.Workshop attendees had the opportunity to tourthe department’s greenhouse and hydroponicfacilities where several hands-on activities tookplace. Krishna Nemali, professor of controlledenvironment agriculture, lead the workshop.Event comprised of both classroom stylepresentations by Drs. Petrus Langenhoven, LauraIngwell and Krishna Nemali and hands-on trainingsessions organized by Alex Miller, JulianaBrustolin, Yuyao Kong, Alex Rodriguez, andRanjeta Adhikari (students and postdoc). A bigthanks to Lori Jolly-Brown for organizing theevent and working behind the scenes to make ita grand success! The event was attended bynearly 80 people.

October 17, 2019 Indiana Flower Growersassociation conferenceRegistration now open!Purdue University, Daniel Turf CenterContact Lori Jolly-Brown, ljollybr@purdue.eduHorticulturists and greenhouse operators willhave an opportunity to network with industryexperts and Purdue Extension specialists.Educational sessions to include technology andautomation, electrical conductivity sensors,marketplace opportunities, greenhouseproduction, worker production standards, as wellas networking with other flower growers acrossthe state.January 7, 2020 Illiana Vegetable GrowersSymposiumTeibel’s Family Restaurant, 1775 US 41, US 30 &US 41, Schererville, INhttps://ag.purdue.edu/hla/Extension/Pages/IVGS.aspxFebruary 11-13, 2020 Indiana HorticulturalConference & ExpoIndianapolis Marriott East Hotel:Contact Lori Jolly-Brown, ljollybr@purdue.eduhttps://www.inhortcongress.org/The Indiana Horticultural Conference & Expo,presented by Purdue University, is an educationalmeeting designed to meet the needs of fruit,vegetable, wine, organics, greenhouse, hightunnel, specialty crop growers and marketers inIndiana and surrounding states. Over 500registrants and more than 70 vendors attendeach year.February 11-13, 2020 Indiana Green ExpoIndiana Convention Center, Indianapolis, INIndiana’s largest, most comprehensive greenindustry event of the year!Offering over 75 educational seminars plus aSpanish track, certification opportunities,in-depth workshops, numerous CEUs and CCHs tobe earned, and a two-day trade show!

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July 30, 2020 Small Farm Education Field DayDaniel Turf Center, Purdue Student FarmContact Lori Jolly-Brown, ljollybr@purdue.edu

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