JASP 3 -- 1985.pdf - International Herbage Seed Group

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36 JOURNAL OF APPLIED SEED PRODUCTION, VOL. 3, 1985CarbofuranResidues of carbofuran or the metabolites were not detectedin alfalfa pollen, nectar or pollen-nectar balls (Table3). Therefore, as with dimethoate, logically the pollinationactivities of the bees should not be impacted. However, thenumber of bee cells constructed on the carbofuran-treatedplots averaged 40% fewer in 1980, and 5% fewer than thecontrol in 1981 (Table 1). Lack of control of detrimentalinsects in mid- to late-season reduced alfalfa flowering.Therefore, the reduced availability of pollen and nectar forthe bees accounts for the reduced number of bee cells. Thepercent cells with cocoons, percent live larvae, and percentpollen-nectar balls compare favorably with the control, withthe exception of percent pollen-nectar balls in 1981. We haveno explanation for the increased pollen-nectar balls in 1981.AldicarbResidues of aldicarb and its metabolites were previouslyreported detected in alfalfa leaves, nectar, and leaf from beecells but not in the pollen-nectar ball (Table 3). Low levels ofaldicarb residues and its metabolites (Table 3) were detectedin samples from plots not treated in 1980 but previouslytreated in 1978 and 1979. High levels of residue were detectedin samples from the leaf from cells from the single plottreated and sampled in 1980.The number of cells constructed in 1980 were I 0% fewerin the aldicarb plot than the control (Table 1). However, thepercent cells with cocoons, percent live larvae and percentpollen-nectar balls generally compares favorably with thecontrol. The one exception is in 1980 when the percent ofcells with cocoons from the untreated aldicarb (treated in1978 and 1979 at 3.36 kg of a.i. ha-I rate) plot produced 64%good cells compared to 74% for the control. Lack of controlof detrimental insects in the nontreated plots resulted infewer alfalfa flowers and thus a diminishing supply of pollenand nectar for the bees. Aldicarb appears to have no adverseeffect on leafcutting bees and their pollination activities at therates used in this study, particular! y when the results of 197 8and 1979 are considered. The aldicarb-treated plots producedthe highest seed yields and had more live bee larvae than thecontrol or the demeton or trichlorfon treated plots in 1978 and1979.Oxydemeton-methylOxydemeton-methyl was applied for the first time in 1981and residues in alfalfa leaves, pollen, nectar, pollen-nectarballs, and leaf from the bee cells are reported (Table 2). Leafsamples for residues of oxydemeton-methyl and its sulfonemetabolite were taken 12 hrs to 14 days after the second spraytreatment and 4 days after the third spray treatment. Residuesranged from a high of 28.9 ppm (12 hrs) to 2.65 ppm (14Table 3. Summary of residues in pollen-nectar (p-n) ball and alfalfa leaf collected by Megachile rotundata from alfalfa seed plotstreated with several insecticides in 1980. (Condensed from George and Rincker, 1982).InsecticideTreatment(kg a.i. ha-l)Sampling interval(Days after application)p-n ballResidue found (ppm)leaf-cellDemeton0.280.42389213892148948926 to 6926 to 6926 to 5426 to 544756600.44 0.020.30 NDI0.27 O.Q70.02 0.050.10 0.020.03 0.060.21 2.970.10 0.0715.675.45 5.770.64 1.080.27 1.140.75 1.240.68 4.48nonenonenonenonenone 0.6 to 10.0none 0.6 to 10.0ND 2.09ND 0.610.12 9.27Trichlorfon1.682.52DimethoateCarbofuranAldicarb0.560.841.121.683.36IBelow lower limit of sensitivity of the method used.
JOURNAL OF APPLIED SEED PRODUCTION, VOL. 3, 1985 37days) after treatment at the recommended rate and 51. 8 ppmto 0.10 ppm, respectively, at the higher rate. High residueswere detected in the nectar 12 hrs after treatment. However,these high residues were not detected in the pollen-nectar ballor leaf from the cell. In spite of these levels of residues, thebees performed well in the treated plots and the insecticideprovided good control of the detrimental insects in the alfalfa.The number of bee cells constructed in 1981 averaged 13%above those from the control (Table 1). Also, the percentcells with cocoons, percent live larvae, and percent pollenballs reflected no adverse effect of oxydemeton-methyl onthe bees or their pollination activities. Oxydemeton-methylwas applied again in 1982 with similar results regarding beeactivities (Rincker, unpublished data).In summary, residues in the leaves and/or the pollen-nectarballs show no adverse effect on bee larvae in this study evenat 1.5 times recommended rates. Bees from cells retainedfrom the 1980 treated plots performed as well in 1981 as beesfrom the control plots. The effect of pesticide residues in thepollen-nectar ball on leafcutting bee larvae has not beenreported previously. Results from this study are not a basisfor using more than the recommended rates of the respectiveinsecticides but are reported as experimental data only.ACKNOWLEDGEMENTWe thank the Washington Alfalfa <strong>Seed</strong> Commission forpartial support of this research project.REFERENCES1. Capizzi, J., G. Fisher, H. Homan, C. Baird, A. Retan, and A.Antonelli. 1982. Pacific Northwest Insect Control Hand-book.pp 23.2. George, D.A., and C.M. Rincker. 1982. Residues of commerciallyused insecticides in the environment of Megachilerotundata. J. Econ. Entomol. 75:319-323.3. Johansen, Carl. 1983. How to reduce bee poisoning frompesticides. Western Region Ext. Publ. (WREP) 15. pp 1-11.4. McGregor, S.E. 1976. Insect pollination of cultivated cropplants. USDA Agric. Handbook No. 496:36-39.5. Waller, G.D. 1969. Susceptibility of an alfalfa leafcutting beeto residues of insecticides of foliage. J. Econ. Entomol.62(1):189-192.Lodging Control and Yield Enhancement in Morex Spring Barley withPaclobutrazol TreatmenttL.A. Morrison and D.O. ChilcotezABSTRACTPaclobutrazol, an experimental plant growth regulator (PGR),is reported to control lodging through height reduction and stemstrengthening and thereby enhance yield. This field experimenttested Paclobutrazol under two levels of nitrogen on a knownlodging-susceptible spring barley cultivar (Hordeum vulgare cv.Morex).Paclobutrazol caused significant shortening of the basal internodesbut did not improve stem strength. Due to delayed lodging,treated plots reflected significant yield increases over the controlplots. The higher treatment rates (800 and 1000 g ha-1) alsoshowed significant yield increases over the lower treatment rates(400 and 600 g ha-1).IA Contribution of the Crop Science Department, OregonState University. Received for publication 30 September,1985.2Formerly Graduate Assistant and Professor of Crop Physiology,respectively, Department of Crop Science, OregonState University, Corvallis, Oregon 97331, USA.The results point to a clear association of reduced height withlodging control and concomitantly with yield increases. Theabsence of improved stem strength raises questions concerningthe mechanism ofPaclobutrazol's effect on lodging in the barleyspecies and the mechanism of its effect in combination withnitrogen fertility.~-------------------------Additional index words: Height reduction, Hordeum vulgare,Parlay, plant growth regulator, stem strength.INTRODUCTIONLodging can be a management problem in intensive culturalsystems where high nitrogen levels and optimum moisturerelations are used to promote yield (Mulder, 1954;Pinthus, 1973). Under these conditions, lodging-susceptiblecereal cultivars , which are typically tall and weak-strawed,show a greater tendency to lodge. Yield losses can be significant,particularly when plants lodge during the earlylodgingperiod that occurs at heading (Laude and Pauli,1956; Pinthus, 1973).Plant growth regulators (PGR's) which affect the stemelongation event by manipulating the endogenous hormonesystems have proven useful in controlling lodging (Froggatt
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