EXPLORING BIOFUMIGATIONAL POTENTIAL OF MUSTARDS

Transcription

1 EXPLORING BIOFUMIGATIONAL POTENTIAL OF MUSTARDS Oleg Dugovish*, (University of Cliforni Coopertive Extension - Ventur County), Jmes Downer nd Ole Beker (University of Cliforni Coopertive Extension -Ventur County nd University of Cliforni-Riverside) The study onduted ner Snt Pul, Cliforni in 22 ompred the effet of tissue mulhing nd onsequent irrigtion on survivl of pthogeni fungus sleroti of Slerotini minor, itrus nemtode (Tylenhulus semipenetrns) (n inditor speies for root-knot nd yst nemtodes - Ole Beker, personl ommunition) nd seed of urlover (Medigo polymorph), nnul ryegrss (Lollium multiflorum) nd pigweed (Amrnthus retroflexus). Orientl mustrd (Brssi june), rd (Sinpis l), f/ell en (Vii f) nd mixture of erel rops of rye (Sele erele) nd tritile (Tritium estivum x Sele erele) were hopped with mower t lte flowering nd resulted mulh ws sprinkler-irrigted with 3 mm (1.2 inhes) of wter within.5 h fter mulhing, similr to method employed y Mtthiessen nd Wrton (22). Breground ontrols were lso inluded. All pthogens were uried in wterpermele gs t 2 m soil depth prior to irrigtion, reovered 7 dys lter nd nlyzed for viility. All plots where split nd hlf of eh plot ws overed with lk PVC plsti fter g uril. Mulh from ll plots ws olleted nd queous extrts were used in lortory for sleroti growth nd weed germintion ssys. Glditor romine lettue (Ltu stiv) nd proprietry vriety (DUDA Cliforni) of elery (Apium grveolens) were plnted in ll field plots (1 y 6 m) following iofumigtion. Addition of ny orgni mteril to the soil used drmti redution in itrus nemtode survivl (Figure 1), while survivl in re ground ontrol ws similr to room temperture stored gs. Nemtode suppression ws 92% greter fter orientl nd rd (with exeption of rd tretment with dditionl plsti) thn fter erel or legume, inditing possile ontriution of mustrd llelohemils to nemtode suppression. Wlker (1997) lso reported 25 to 81% redution in itrus nemtode popultion fter soil ws mended with 4 to 8 g/kg soil of tissue of severl Brssi speies. Biofumigtion in the field did not ffet growth of sleroti (Figure 2) of Slerotini minor, exept when orientl mustrd ws used in omintion with plsti (75% redution in growth ompred to ontrol). Results from other tretments pper inonsistent nd highly vrile. The effet of orientl mustrd tissue extrts on sleroti growth ws further ssessed in the lortory. No sleroti grew in queous extrts from orientl mustrd tissue (Figure 3) nd sleroti growth ws redued out 6% in tissue extrts from tretments: orientl mustrd + plsti nd erel. Orientl mustrd ws superior to other rops in inhiiting sleroti growth in oth field nd l tests. However, the

2 mehnism inhiiting sleroti growth in the l my not hve een fully employed in the field, resulting in some vile sleroti. This my indite tht sleroti in the field were exposed to lesser onentrtion of mustrd-derived llelohemils thn in l extrts. Identifition of the onentrtion mesurements of llelohemils thought to e responsile for pthogen suppression is neessry to test this hypothesis. Aundnt presene of Trihoderm sp. (the fungi with ioide potentil) ws oserved in pltes with sleroti from oth field nd l isoltes from orientl mustrd plots. This oservtion is in greement with results of Smith (21), whih doumented prolifi growth of Trihoderm sp. t ITC onentrtions well eyond wht killed pthogeni fungi suh s Gemnnomyes grminis (tke-ll disese), Pythium sultum (vity spot of rrots), nd teri Rlstoni solonerum (teril wilt). This suggests tht dynmi hnges in miroiologil ommunity my e prtilly responsile for iofumigtion effets of Brssi sp. on ertin soil-orne pthogens. No inhiition in weed seed emergene ws oserved in the field (dt not shown). However, in the l queous tissue extrts of orientl mustrd ompletely inhiited germintion (Figure 4) while urlover nd pigweed did not germinte in f en tissue extrts. Lk of weed suppression in the field nd omplete weed germintion inhiition in the l orrespond with findings of Slerotini minor ssys. This gin indites the need for identifition of llelohemils nd orreltion of their onentrtion with suppression of soil-orne pests nd weed germintion inhiition. Infetion of romine lettue with Slerotini minor ws 91 nd 68% lesser fter iofumigtion with nd orientl mustrd, respetively, thn fter f en (Figure 5). Lettue following rd + plsti ws nerly infetion-free (7.6 times lesser infetion sore thn ontrol). Yellow mustrd + plsti tretment onsequently resulted in the lrgest lettue heds t the time of hrvest (Figure 6). Bre-soil ontrol hd more weeds thn other tretments (dt not shown), likely due to the sene of plnt residue, thus, resulting in lightest lettue heds (Figure 6). Similrly, elery plnts were lightest in re-soil ontrol tretment (Figure 7) ut hd the gretest weight following iofumigtion with mustrds (46% more thn fter f ens nd 73% more thn fter re soil ontrol). This study t Snt Pul, CA nd reports from reviewed literture show enefiil effets of mustrd speies on susequent rop plntings. However, it is unler whih llelohemils where the most suppressive for pest nd pthogens studied t Snt Pul, CA nd if lk of suppression ws result of low or low onentrtions of those llelohemils. RERERENCES Mtthienssen J. nd B. Wrton. 22. Plnt mertion nd moisture hold the key to the iofumigtion suess. Hortiulture Biofumigtion Updte 15:1-2. CSIRO Entomology, PO Wemley, WA 614, Austrli.

3 Smith B. 21. A omplex mode of tion for iofumigtion? Hortiulture Biofumigtion Updte 13:1. CSIRO Entomology, PO Wemley, WA 614, Austrli. Wlker G Brssis tive ginst itrus nemtode. Hortiulture Biofumigtion Updte 6:2. CSIRO Entomology, PO Wemley, WA 614, Austrli.

4 Citrus nemtode (Tylenhulus semipenetrns ) survivl following iofumigtion 3 2d stge juveniles/ ontrol ontrol+plst erel erel+plst g orientl must fg orientl must+plst g ef must+plst f en ef f en+plst Figure 1. Survivl of itrus nemtode following iofumigtion t Snt Pul, CA in 22. Tretments re: ontrol (re ground), f en, Pifigold' orientl mustrd, Idgold' rd, erel mixture of rye nd tritile; + plst' indite presene of PVC plsti during iofumigtion % sleroti grown Slerotini minor growth in l following soil iofumigtion room stored ontrol ontrol+ plst F F+ plst orientl must orientl must+plst must+plst Figure 2. Growth of sleroti of Slerotini minor following iofumigtion t Snt Pul, CA in 22. Tretments re: ontrol (re ground), f en, Pifigold' orientl mustrd, Idgold' rd, erel mixture of rye nd tritile; + plst' indite presene of PVC plsti during iofumigtion erel erel+plst

5 Slerotini minor growth in l in plnt tissue extrts 1 % sleroti grown ontrol wter f en orientl must orientl must+plst erel Figure 3. Growth of sleroti of Slerotini minor in lortory in queous plnt tissue extrts germintion, % Weed seed germintion in plnt tissue extrts ontrol wter f en orientl must erel urlover ryegrss pigweed Figure 4. Germintion of urlover (Medigo polymorph), nnul ryegrss (Lollium multiflorum nd pigweed (Amrnthus retroflexus) in lortory in queous plnt tissue extrts

6 infetion sore re ontrol+plst Infetion of romine lettue 'Glditor' with Slerotini minor following iofumigtion re ontrol f en+plst f en must+plst = no slerotini -.4 = some myelium on outer lefs.4-.8 = myelium >.8 = myelium + sleroti or ded plnt orientl must+plst Figure 5. Infetion of romine lettue Glditor' with Slerotini minor following iofumigtion t Snt Pul, CA in 22.Tretments re: ontrol (re ground), f en, Pifigold' orientl mustrd, Idgold' rd, erel mixture of rye nd tritile; + plst' indite presene of PVC plsti during iofumigtion orientl must Hed weight of romine lettue 'Glditor' following iofumigtion 1 g / hed re ontrol+plst re ontrol f en+plst f en must+plst orientl must+plst Figure 6. Individul hed weight of romine lettue Glditor' following iofumigtion t Snt Pul, CA in 22.Tretments re: ontrol (re ground), f en, Pifigold' orientl mustrd, Idgold' rd, erel mixture of rye nd tritile; + plst' indite presene of PVC plsti during iofumigtion orientl must

7 Celery plnt weight following iofumigtion 25 g / plnt d re ontrol+plst re ontrol f en+plst f en must+plst orientl must+plst Figure 7. Individul plnt weight of elery following iofumigtion t Snt Pul, CA in 22. Tretments re: ontrol (re ground), f en, Pifigold' orientl mustrd, Idgold' rd, erel mixture of rye nd tritile; + plst' indite presene of PVC plsti during iofumigtion. orientl must