SUMMARYA study was made of the effects of concentrations of 2 to 32 ppm of oximecarbamate, organophosphate and benzimidazole nematicides on the hatch, larval viability and migration of Meloidogyne javanica, M. incognita and M. hapla and on development of M. javanica in roots. Aldicarb at less than 8 ppm had little effect on hatch and methomyl markedly affected only the hatch of M. hapla. As little as 2 ppm of fenamiphos or thionazin markedly reduced hatch of all three species but less than 8 ppm ethoprophos significantly reduced only the hatch of M. incognita and phorate had little effect on hatch. Benomyl and thiabendazole had no significant effects on hatch. When egg masses of M. incognita were transferred from nematicides which suppressed hatch to water, hatching occurred, but aldicarb, fenamiphos, ethoprophos and thionazin significantly reduced total hatch.None of the nematicides killed larvae of the three species immersed in 16 and 32 ppm solutions of them for 3 days. Aldicarb at 2 ppm reduced migrations of all three species; the effects of methomyl, fenamiphos or thionazin on migration varied according to species, while phorate, ethoprophos, benomyl or thiabendazole had little or no effect on migration. Aldicarb or thionazin at 2 ppm stopped development of M. javanica in roots of tomato seedlings while methomyl, ethoprophos or fenamiphos at 4 ppm reduced development by 60% and at 8 ppm of ethoprophos or fenamiphos or 16 ppm of methomyl, development was stopped. Phorate had little effect on development and benomyl or thiabendazole had no effect. Nematicide concentrations which reduced development prevented the normal orientation of larvae in the roots and reduced or prevented giant cell formation.

The grape production and grape and wine quality of Shiraz vines, grown either on their own roots or on 6 rootstocks that have varying resistance to nematodes, were compared. Vines on the rootstocks Ramsey and Dog Ridge outyielded ungrafted vines by 46 and 48%, respectively, principally because of increased vegetative growth and hence retention of more nodes at pruning. Ramsey rootstock gave a greater grape yield per shoot. The ability of Dog Ridge stocks to produce yields as high as those of Ramsey highlights the importance of adequate pruning levels to enable the full potential of rootstocks to be determined. Vines on the rootstock Dog Ridge produced wines with higher pH values than wines from ungrafted control vines. Nematode counts suggested that the Vitus champini stocks have good tolerance to both rootknot and root lesion nematodes.

Factors responsible for a decline in wheat yields in some paddocks in the Gunnedah (northern New South Wales) area were investigated in a series of field experiments. Yield decline is not apparent on soils cultivated for less than 10 years, and barley and sorghum crops are not affected. Plant nutrition apparently is not a major factor in the decline, because, although there was a small response to zinc application in 1 experiment, wheat yields were not significantly increased by the application of N, P, K, Cu, Mg, B, Mn, Mo or S in a paddock where the yield of wheat was half that of the surrounding barley crop. Fumigation of the soil with methyl bromide increased wheat cv. Timgalen yield by 78% to equal that of barley cv. Clipper in a second experiment. Large numbers of root lesion nematodes (Pratylenchus thornei) were associated with unfumigated wheat plots, with smaller numbers present on barley plots. In a third experiment, the grain yields of all of the 9 cereal genotypes tested were increased when sown with 4 kg/ha of aldicarb. The relative yield increase associated with aldicarb showed good correlation with the reputed tolerance of the genotypes to P. thornei. Pratylenchus thornei occurred to a depth of 120 cm. Aldicarb did not affect P. thornei numbers below 15 cm, while methyl bromide controlled P. thornei to depths of 30-90 cm. Aldicarb virtually eliminated P. thornei from the surface 10 cm of soil, but had no effect on the incidence of the fungal diseases common root rot (Bipolaris sorokiniana) or crown rot (Fusarium graminearum). Soil fumigation with methyl bromide controlled B. sorokiniana and F. graminearum as well as P. thornei and gave yields 9% higher than did treatment with aldicarb. In another experiment, ethylene dibromide (2.7-10.8 L/ha) had no consistent effect on the yield of wheat or numbers of P. thornei while terbufos (0.6 and 1.2 kg/ha) gave a small reduction in P. thornei numbers and a small increase in yield. These data indicate that P. thornei is at least partially responsible for wheat yield decline in parts of northern New South Wales.

No abstract

Commercially produced freeze-dried cultures of Rhizobium have been tested for suitability when used directly as legume inoculants. They compared favourably with commercial peat cultures in the number of viable cells per culture and gave comparable nodulation in three field trials. They were less perishable than peat cultures particularly at high temperatures (37�C).