Response of soybean cyst nematodes to herbicide application on soybeans

The effect of herbicide applications to V3 soybeans on the reproduction of race 3 soybean cyst nematode (SCN) was measured. The hatching response of SCN eggs to soybean root exudates collected after postemergence herbicide application, the viability of SCN eggs formed on treated plants and the levels of glyceollin in roots of treated soybeans were also measured. Soybeans were treated postemergence with 1X and 2X rates of herbicides plus a recommended adjuvant and/or the adjuvants alone. None of the treatments tested were found to stimulate SCN reproduction. Acifluorfen, bentazon, lactofen, crop oil concentrate (COC) and nonionic surfactant (NIS) treatments reduced soil populations of SCN by 50 to 60% at four and eight weeks after application when compared with the untreated control. Fluazifop-P, sethoxydim, and imazethapyr treatments had no effect on SCN reproduction. Adjuvant treatments were as effective as acifluorfen, bentazon, and lactofen treatments in reducing SCN reproduction. However, no additive effect for adjuvant-herbicide combinations was observed nor did herbicide rate affect SCN reproduction. Treatments reduced SCN reproduction only when applied to soybean plants and exhibited no effect when applied to the soil. All root exudate solutions (RES) increased SCN hatching more than deionized water, but less than ZnSO4 solutions. However, no statistical differences due to herbicide treatment were observed. Filter sterilization of RES increased SCN hatching when compared with the use of non-sterile exudates. Acifluorfen, bentazon and lactofen treatments negatively affected the hatching potential of SCN eggs from adult females that developed on treated plants. Acifluorfen, bentazon, COC and NIS treatments also increased glyceollin levels in soybean roots four days after application. Glyceollin has been shown to accumulate in some soybean roots following infestation with SCN and has been implicated in SCN resistance. Therefore, these herbicide treatments may have indirectly induced a level of SCN resistance in a susceptible soybean, thus lowering SCN reproduction. The use of some postemergence herbicides may be expanded to include SCN management

Persistence of the nematicide fluensulfone in potato (Solanum tuberosum ssp. tuberosum) beds under field conditions

As part of a broader study to evaluate the efficacy of fluensulfone for control of the potato cyst nematode, Globodera pallida, two field experiments in Shropshire (at Woodcote and Howle in 2010 and 2011, respectively) England, were used to monitor the persistence of fluensulfone in potato beds treated with Nimitz 15G® (fluensulfone) at 27kg ha−1. Fluensulfone dissipated at similar rates in the two fields, with a trend best described by a sigmoidal curve. The time to 50% dissipation (DT50) was 24.3 days at Woodcote,and 23.7 days at Howle. No differences were found between the DT 50for fluensulfone and that observed for fosthiazate. The short DT50 demonstrated for fluensulfone in this study is a positive attribute as this nematicide may pose a negligible hazard to the environment. However, its persistence at an effective dose may be long enough to be effective over the peak hatch period of G. pallida

Chemical control of Meloidogyne spp. in grapevines (Vitis vinifera)

Objective: to determine the effect of increasing rates of Mocap® 6EC (ethoprophos-AMVAC) on grape (Vitis vinifera) own-rooted cv. Flame and cv Red Globe grafted onto Quebranta rootstock Meloidogyne spp. control. Methodology and Results: two field experiments of increasing rates of 0, 6, 8, 10, and 12 L ha-1 of Mocap® 6EC (ethoprophos-AMVAC) using a complete randomized block design with 4 replicates were set up on grape (Vitis vinifera) own-rooted cv. Flame and cv Red Globe grafted onto Quebranta rootstock for Meloidogyne spp. control. To quantify nematode numbers in soil and roots, and the number of galls in a linear meter root, soil and root samples were taken just before treatment and at 30, 60 and 90 days after product application. In both experiments, at 30, 60 and 90 days after the application, a decreasing linear effect on Meloidogyne spp. numbers in soil (P< 0.0001) and roots (P≤ 0.0002) and number of galls (P< 0.0001) was observed as rate increased. The average reduction was of 4.6, 4.9 and 5.2; and 5.5, 6.0 and 6.3 individuals per 100 g of soil, and 5.6, 9.9 and 9.9, and 4.9, 7.7 and 8.2 nematodes per 100 g of roots, and 2.0, 4.0 and 4.3, and 1.8, 3.9 and 4.9 galls per linear meter of root, by every litre of increase on the applied rate, at 30, 60 and 90 days post application, for the experiment at Ica and Lima department, respectively. Differences in biological efficacy among rates were found for soil (P< 0.0001) and root (P< 0.0001) nematode control, and number of root galls (P< 0.0001), increasing the control as the rate increased in both experiments. Efficacy in soil nematode control varied from 51 to 98% and 73 to 99%, in roots it varied from 61 to 85% and 61 to 87%, and in the number of root galls from 55 to 84%, and 58 to 81% for the experiment at Ica and Lima department, respectively. Conclusions and application of findings: All Mocap® 6EC rates tested reduced Meloidogyne spp. in soil and roots, and the number of galls per linear meter of root, with higher reductions as the rate increased. Then the recommended rate is 10-12 L ha-1 incorporated in a drip irrigation of two hours.Key words: chemical control, grapevines, Meloidogyne, nematode control

Field evaluation of the nematicide fluensulfone for control of the potato cyst nematode Globodera pallida

BACKGROUND Three field experiments evaluated the performance of the nematicide fluensulfone against the potato cyst nematode Globodera pallida in Shropshire, England. RESULTS Experiments 1 and 2 showed reduced root infection and lowered multiplication of G. pallida following fluensulfone (Nimitz 15G®) soil treatments at five rates (1.95, 3.00, 4.05 (full rate), 5.05 and 6.00 kg AI ha−1) and Nimitz 480EC® at the full rate. Experiment 3 demonstrated a positive interaction between the full rate of Nimitz 15G and the potato variety Santé in the reduction of G. pallida. The fluensulfone treatments at the full rate had more consistent effects than the lower rates, and there were no greater effects for the treatments higher than this full rate. Generally, fluensulfone was less efficacious than oxamyl or fosthiazate, which suggests that the treatment may not be reliably integrated within shorter potato rotations. CONCLUSION The data suggest that fluensulfone soil application could make a useful addition to the few available nematicide treatments for the control of G. pallida rather than be a substitute for these treatments