Celery. Wednesday afternoon 2:00 pm. Moderator: Amy Irish-Brown, MSU Extension Fruit & Vegetable. 2:00 p.m. New Products for Foliar Blights

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New Products for Folir Blights Ryn Bounds, Plnt Pthology Dept., MSU 2:3 p.m.

1 Celery Wednesdy fternoon 2: pm Modertor: Amy Irish-Brown, MSU Extension Fruit & Vegetle 2: p.m. New Products for Folir Blights Ryn Bounds, Plnt Pthology Dept., MSU 2:3 p.m. Insect Mngement in Celery Beth Bishop, Entomology Dept., MSU 3: p.m. Fusrium Resistnce in Celery Rebecc Grumet, Horticulture Dept., MSU

2 New Products for Folir Blights R.S. Bounds (Grdute Student) nd Dr. M.K. Husbeck ( ) Michign Stte University, Deprtment of Plnt Pthology Folir diseses of celery my reduce qulity nd yield if not properly mnged. Lte blight is fungl disese cused by Septori piicol. It is identified by the presence of smll, blck pycnidi embedded in irregulrly-shped lesions on leves or scttered throughout discolored tissue on petioles. Spores of the fungus re spred by splshing wter nd require free wter to infect plnts. Bcteril lef spot of celery is cused by Pseudomons syringe pv. pii. The disese ws previously known s northern bcteril blight. The lesions only pper on leves nd re initilly wter-soked round the mrgin. Lesions of bcteril lef spot my resemble those of lte blight but cn esily be distinguished by the presence or sence of pycnidi. Testing Products for Control of Lte Blight Fungicides were evluted t the MSU Muck Soils Reserch Frm in 25 (Tle 1). Sevenweek old celery Dutchess trnsplnts were plnted 7 in. prt in rows spced 32 in. prt on 25 My. Tretment plots consisted of one row 2 ft long with 5 ft of unspryed buffer between plots in the sme row. Twelve tretments were replicted four times in rndomized complete block design. Inoculum ws pplied with hnd-pump bckpck spryer to ll plnts in the tril severl hours fter tretments were pplied on 6 nd 13 Jul using one hollow cone nozzle tht delivered pproximtely 12 gl/a. Fungicides were pplied with CO 2 bckpck boom spryer equipped with three XR83 flt fn nozzles spced 18 in. prt nd clibrted to deliver 5 gl/a t boom pressure of 52 psi. Six pplictions were mde t weekly intervls on 6, 13, 21, nd 27 Jul; nd 3 nd 11 Aug, except for the biweekly tretment of 82.5WDG which received three pplictions on lternte dtes. Lef blight severity ws evluted on 11 nd 16 Aug, nd ten plnts from the middle of ech tretment row were hnd-hrvested nd trimmed to fresh mrket specifictions (14 in. length) on 17 Aug. Petiole disese incidence nd severity were ssessed, disesed petioles were removed from the plnts, nd yields were recorded. Tle 1. Products tested for control of lte blight of celery, 25. Product Active ingredient(s) Mnufcturer Registered Amistr 8WG zoxystrobin Syngent yes Botrn 75-W diclorn Gown yes 82.5WDG chlorothlonil Syngent yes Wether Stik 6SC chlorothlonil Syngent yes Endorse 11.3DF polyoxin D zinc slt Arvest no Endur 7WG bosclid BASF no 53.8DF copper hydroxide DuPont yes Pristine 38WG bosclid + pyrclostrobin BASF no Serende Mx 2WP Bcillus subtilis AgrQuest yes Tilt 3.6EC propiconzole Syngent yes TM 473 experimentl -- no

3 Disese symptoms ppered on leves throughout the plot on 18 Jul. Untreted plnts were severely disesed t hrvest which resulted in extensive trimming nd low yield (Fig. 1). Four fungicide progrms provided seson-long disese prevention on petioles nd included Amistr 8WG lternted with Tilt 3.6EC, Amistr 8WG lternted with 82.5WDG, Pristine 38WG lternted with 82.5WDG, nd 82.5WDG pplied weekly. Trimmed yields of the TM 473 4F lternted with 82.5WDG nd biweekly 82.5WDG progrms did not differ from the progrms tht prevented petiole disese. Tretments tht included Endur 7WG or Endorse 11.3DF offered limited protection nd were generlly inferior to the stndrd 82.5WDG weekly tretment. Applictions of Serende Mx 2WP lternted with 82.5WDG, 53.8DF, nd Botrn 75-W were ineffective in limiting lte blight nd resulted in similr disese levels nd yields when compred to the untreted control. No phytotoxicity ws observed. Figure 1. Efficcy of products tested for controlling lte blight of celery, 25. Lef blight severity (%) de Brs with the sme letter re not significntly different b c d de e 1 8 Disesed petiole re (%) cd b c cd d Mrketle yield / 1 plnts (lb) d Tretments pplied t 7-dy intervls, except where noted bc cd d d d Untreted Amistr 5 oz/a lt. Tilt 4 fl oz/a Amistr 5 oz/a lt. Pristine 1.5 oz/a lt. TM fl oz/a lt. Wether Stik 1.5 pt/a (14-dy intervl) Endur 4.6 oz/a Endorse 7 oz/a lt. Serende Mx 2 lb/a lt. Botrn 2 lb/a

4 Testing Products for Control of Bcteril Lef Spot Products were evluted t the MSU Muck Soils Reserch Frm in 25 (Tle 3). Eight tretments were replicted four times in rndomized complete block design. Eleven pplictions were mde t weekly intervls on 1, 8, 16, 22, nd 29 Jun; 6, 13, 21, nd 27 Jul; nd 3 nd 11 Aug. Disese developed from nturlly-occurring inoculum on trnsplnts. Ten plnts from the middle of ech tretment row were hnd-hrvested, trimmed to fresh mrket specifictions (outer petioles removed nd plnts cut to 14-in. length), nd weighed on 17 Aug. Since little difference in disese levels were detected mong tretments on 17 Aug (dt not shown), four dditionl plnts were hnd-hrvested from ech tretment row nd evluted for disese on 3 Aug. Outer petioles were removed, similr to the procedure for trimming plnts to fresh mrket specifictions, but the upper folige ws not removed. Disese incidence ws determined by counting the totl number of mrketle petioles (those where the first node mesured > 9 in. ove the bse of the plnt) nd the number of mrketle petioles with disese symptoms on the leves. Disese severity ws visully ssessed by estimting the percentge of lef re with bcteril lef spot symptoms on plnts tht were not hrvested. Tle 3. Products tested for control of bcteril lef spot of celery, 25. Product Active ingredient(s) Mnufcturer Registered Actigrd 5WG cibenzolr-s-methyl Syngent no Citrplex 2% Copper copper sulfte Lovelnd yes EPA exempt 53.8DF copper hydroxide DuPont yes* Messenger STS 3WDG hrpin protein Eden Bioscience yes* Serende Mx 2WP Bcillus subtilis AgrQuest yes* Tnos 5DF fmoxdone + cymoxnil DuPont no * Products leled for greenhouse nd field use. Disese symptoms ppered on newly expnded leves on 8 Jun. The cusl gent ws confirmed s Pseudomons syringe pv. pii by BIOLOG nlysis conducted by Dignostic Services t Michign Stte University. All product tretments, except those tht included Serende Mx 2WP or Citrplex 2% Copper, reduced lef spot severity reltive to the untreted control (Fig. 2). Applictions of Actigrd 5WG DF resulted in the lowest lef spot severity but did not differ from the stndrd tretment of 53.8DF pplied lone. No significnt rte response ws observed when 53.8DF ws pplied t 1 lb or. Only Serende Mx 2WP DF significntly reduced disese incidence reltive to the untreted control, yet the tretment ws not superior when compred with other product tretments. No phytotoxicity ws observed.

5 Figure 2. Efficcy of products tested for controlling bcteril lef spot of celery, c Brs with the the sme letter or or no no letter re re not not significntly different bc Lef blight severity (%) c Petioles with disesed leves (%) b Mrketle yield / 1 plnts (lb) Tretments pplied t 7-dy intervls Untreted Actigrd.5 oz/a + Tnos 8 oz/a + lt. 1 lb/a Messenger 6 oz/a + Serende 3 lb/a + Citrplex 8 oz/a

6 Insect Mngement in Celery Beth A. Bishop Deprtment of Entomology Michign Stte University (517) A number of insect pests impct the yield nd qulity of celery. Control of ster lefhoppers, phids nd trnished plnt bugs rnks s top priority for profitle celery production. Aster lefhoppers trnsmit the disese ster yellows, which ffects the growth nd qulity of celery. Aster lefhoppers migrte into Michign ech yer. The risk of ster yellows trnsmission is dependent on the prevlence disese in the lefhoppers. The proportion of ster lefhoppers crrying ster yellows vries from yer-to-yer, loction-to-loction, nd over the seson. The proportion of ster lefhoppers crrying ster yellows (% infectivity) directly ffects the risk of disese nd, thus, the threshold t which insecticide tretment is required. A formul developed by reserchers t the University of Wisconsin is commonly used to estimte tretment threshold: Aster Yellows Index = (number of lefhoppers/1 sweeps) x (% infectivity) Or: Tretment Threshold (lefhoppers/1 sweeps) = AY Index divided by %infectivity Tretment thresholds re determined in celery using n ster yellows index of 35. For exmple, t 1% infectivity the tretment threshold is 35 ster lefhoppers per 1 sweeps. At 2% infectivity, it is 17 nd t 5% it is 7. Since 21 we hve been testing ster lefhoppers to determine infectivity rtes. Besides informing growers so they cn mke tretment decisions, our results provide bse of informtion out how the infectivity rte vries. In 25 Dignostic Services begn testing ster lefhoppers. Lefhoppers from 18 different loctions in Michign were collected by crop consultnts nd extension personnel, nd were sent to Dignostic Services. Lefhoppers from ech site were collected on multiple dtes from two to 17, depending on the site. Results were provided to growers, scouts nd consultnts. There ws lrge vrition in percent infectivity between different geogrphic res. Infectivity rtes lso vried between loctions in the sme geogrphicl re. The infectivity rte of lefhoppers collected from single loction vried considerly over the seson. The sesonl pttern in infectivity rte ws different in different loctions. Trnished plnt bugs feed on celery petioles by inserting their bek nd sucking sp. Their feeding scrs ( stings ) cuse cosmetic dmge, tissue deth, nd my promote bcteril rot. Trnished plnt bugs feed on mny different plnts. Their preference for one kind of plnt over nother is influenced by the growth stte nd condition of ech plnt. Consequently, celery my become ttrctive unpredictly, nd only in comprison with surrounding vegettion. Furthermore, trnished plnt bugs re strong fliers, nd cn move in nd out of celery field quickly, mking their detection difficult.

7 Insecticide tests in the field nd in the l during the pst two yers hve indicted tht severl different insecticides (registered nd not yet registered) show promise for controlling trnished plnt bug on celery. Both Admire (Byer) pplied t plnting, nd Assil (Cerexgri) s folir spry performed s good or better (higher mortlity, lower feeding injury) thn the stndrd insecticide (Sevin XLR+ ) in lortory tests. Feeding by phids (most often, green pech phids nd sunflower phids) cuses distorted growth nd the phids themselves re contminnts t hrvest. Aphid problems re more common during hot, dry wether; phids re serious problem during some yers, but not others. Becuse phid popultions cn grow quickly during the summer, successful control involves timely detection plus use of effective insecticides with short prehrvest intervls. Results of insecticide efficcy tests during the pst two yers hve shown tht the neonicitinoid insecticide, imidcloprid pplied t plnting (Admire ) significntly decresed the number of phids on celery plnts in the l nd reduced the number of plnts showing phid dmge in the field.

8 Breeding for Fusrium resistnce in celery. Rebecc Grumet, Deprtment of Horticulture, Michign Stte University, nd Brin Cortright, Deprtment of Plnt Pthology, Michign Stte University. The breeding progrm for Fusrium resistnt celery t Michign Stte University hs entered the finl stges. Five bulked breeding lines, ech composed of seed from severl relted fmilies, were tested in replicted tril in Hudsonville, Michign, nd in row trils on grower coopertor frms. All breeding lines performed well t ll loctions, with verge disese rtings over ll three loctions of 1. for four of the lines nd 1.1 for one line (on scle of 1-5 where 1 = no disese; 5=>5% crown discolortion). The commercil lines included for comprison lso hd low disese rtings, 1.3 or less. Yields of the breeding lines were somewht lower thn the commercil checks Duchess nd Sros, but not lower thn Picdor or Peto 285. Seed ws sent to Cliforni for medium-scle seed increse.

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