Efficacy of Selected Insecticides Against Phormium Mealybugs on New. Zealand Flax, Phormium tenax.

Transcription

1 1 Effiy of Seleted Insetiides Aginst Phormium Melyugs on New Zelnd Flx, Phormium tenx. Phormium tenx v. Dzler Jmes A. Bethke Pest Teh West Ornge St. Wildomr, CA (951) Ojetive: To determine the effiy of severl neoniotinoid nd other seleted insetiides ginst melyugs. Ornmentl protool numer: Mterils nd Methods Host Plnt nd Insets: Trils were onduted on the property of Sunrest Nursery, Wtsonville, CA. Phormium melyug infested New Zelnd flx (pprox. 4ft 3 volume) in 7 gllon pots were provided y Sunrest Nursery. Phormium ws plnted in ommon nursery mix, Sunrest Nursery Division Mix FGB Yrd. The proportions of produts in the mix re s follows: redwood 60%, Perlite 25%, snd 15%, Ferrous sulfte 20%, Apex nutrients 1/2l/yd, Sottkote fertilizer10l/yd, Potssium nitrte l/yd, nd wetting gent 1oz/yd.

2 2 Plnts were red for under the nturl growing prties y the grower. They were sped s norml, pprox 18 prt, nd overhed irrigted y Rinirds one per dy or s needed (Figure 1). Typil wether ondition inluded erly morning fog nd low louds lmost dily throughout the tril. Tempertures verged F highs exept for pek of 93 F on 23 July, nd F lows. Only tre mounts (<0.05 ) of rinfll were deteted during the tril proly from low louds nd fog on 21, 25, nd 27 July. White wxy residues from the melyugs were present on the lower mrgins of the lower leves of most plnts inditing tht the plnts were moderte to hevily infested t the time of the tril. Phormium leves fold for out the first two-thirds of the lde from the soil line up then lef out like grss for the lst third. Leves were ll sizes during the tril, pproximtely 85m long nd out 4m wide. The melyugs typilly unhed in the fold just ove the soil surfe (see Figure 1). Common tretments pplied y the grower for melyug ontrol re Preise (ephte inorported into slow relese fertilizer) t 1 Tls/pot nd Tristr (etmiprid) t 2pkt/100 gl. Experimentl Design nd Smpling: A rndomized omplete lok design with six replites per tretment ws used in this study. A single lef per plnt ws removed nd ll melyugs within the lef lde were ounted under mirosope. Post-tretment ounts were mde 1, 2, 4, nd 6 weeks fter tretment. An ANOVA (SAS, GLM proedure) ws used to nlyze the dt. Dt were trnsformed x prior to nlysis to stisfy the ssumptions of the nlysis of vrine. Mens were seprted y LSD (p = 0.05) following signifint tretment effet.

3 3 Pestiide Tretment Applitions nd Rtes: Tretments were pplied t the following rtes: 2 nd 4oz/100 gl; 2 nd 4pkets/100 gl; Sfri 4 nd 8oz/100 gl; Sfri 12 nd 24oz/100 gl, nd 1 tlespoon/pot. Folir pplitions of Flgship, Tristr, nd Sfri inluded 0.25% Silwet s wetting gent. New Zelnd flx is grssy plnt nd very diffiult to wet. Control pplitions were mde using wter nd 0.25% silwet. Preise nd ll folir pplitions were pplied twie, two weeks prt. The first pplition ws mde on 1 July 2005 followed y the seond pplition on 13 July Wter t the time of pplitions ws ph of 6.8. Tretment pplitions were mde using Solo kpk spryer t psi nd stndrd flt fn nozzle nd direted t the lower two-thirds of the leves. Plnts were spryed until it ws ovious the leves were wetted y the solutions, nd pproximtely 90 ml of solution ws pplied to the ottom third of eh potted plnt. Drenh pplitions were mde using grdute ylinder nd mesuring out 90 ml of eh formulted solution. The solution ws then spred evenly round the perimeter of eh pot. Phytotoxiity Rtings: A rting system of 1 10, no dmge to plnt deth, ws used to rte phytotoxiity of tretments. Rtings were mde on weeks 2 nd 4 following tretment pplition. An nlysis of vrine ws used to determine differenes etween tretments nd ontrol. Oserved dmge inluded yellow leves, lk spots, split leves, holes in leves, dry ends nd neroti lesions.

4 4 Tril Results Phytotoxiity: Phytotoxiity rtings were not signifintly different etween tretments two weeks fter single pplition, F = 0.88; df = 9,50; P = Two weeks fter seond folir pplition, there ws signifint differene etween tretments, F = 6.5; df = 9,50; P < Folir pplitions of Tristr t oth rtes nd Sfri t the low rte of 4oz rted signifint phytotoxiity ompred to the Control (Figure 2). Very smll lk spots were oserved on most of the plnts prior to pplitions nd typilly on the unfolded lde of the plnts, the prt of the plnt tht ws not treted. These spots re typilly ssoited with teril spot diseses nd not phytotoxiity. A different person took the seond ssessment nd gve the lk spots more weight thn ws given during the first ssessment. Sine spotting ws mjor ftor in rting the plnts for phytotoxiity or dmge, ws most likely not used y the tretment pplitions, nd the ft tht the dmge rtings re fr elow eonomi dmge, the sttistil differenes etween tretments re negligile nd re not iologilly signifint. Although not ddressed in the sttistil nlysis, phytotoxi retion ws oserved in the Preise (ephte) tretment. The grnules would ollet nd onentrte in the lde folds of some of the leves ner the soil surfe nd use serious neroti wounds nd some lef deth. No serious phytotoxi effets were oserved for ny other tretment throughout the rest of the tril. Effiy Tril: Pre-tretment ounts of live melyugs for ll tretments were stndrdized for pplition nd were not signifintly different from eh other, F = 0.64; df = 9,45; P = (first r in eh tretment, Figure 3). Following

5 5 pplition, there ws signifint differene etween tretments throughout the rest of the tril, Week 1 F = 3.8; df = 9,45; P = , Week 2 F = 2.65; df = 9,45; P = , Week 4 F = 7.45; df = 9,45; P < , Week 6 F = 11.84; df = 9,45; P < (Figure 3). Flgship t oth rtes, Sfri t oth rtes s folir spry nd drenh, nd Tristr t oth rtes worked very well in ontrolling phormium melyug. The stndrd, Preise (ephte), ws signifintly different thn the ontrol for only weeks four nd six following pplition nd ws only suppressive t est. Considering tht Preise lso used some notiele phytotoxiity, neroti wounds to plnt prts, it is proly not very good option or solution to phormium melyug infesttions. On the other hnd the other grower stndrd tretment of Tristr worked very well nd used signifint mortlity ompred to the ontrol for ll smpling dtes. Conlusions One of the stndrd tretments the grower ws using, Preise (ephte), is poor hoie for ontrol of phormium melyug euse of the lk of effiy nd the potentil for phytotoxiity. Tristr (etmiprid), however, the other stndrd, is still good hoie for ontrol y the grower. In ddition, folir pplitions of Flgship nd Sfri re lso good lterntives, nd Sfri my lso e used s drenh pplition nd for good ontrol of phormium melyug.

6 6 Figure 1. Top left. Field tril lotion nd plnt distriution. Top right. Phormium melyug evidene, white wxy otings t the se of leves. Bottom left. Lef pulled down to expose melyugs nd wxy oting on next lef in suession. Bottom right. Phormium lef lde pulled prt to expose well proteted phormium melyugs.

7 7 Figure 2. Phytoxiity rtings from four weeks fter tretment for Phormium treted with seleted insetiides

8 8 Figure 3. Men numer of live melyugs per phormium lef treted with seleted insetiides. 80 Week Week 1 Week 2 Week 4 Week d d d 10 0 Control Flgship 2oz d d Flgship 4oz d d d d Preise 1 tls/pot Sfri 12oz drenh Sfri 24oz drenh d Sfri 4oz Sfri 8oz Tristr 2pkt Tristr 4pkt d d d 0.25% ws dded to the folir pplitions of Flgship, Tristr, nd Sfri.