VERMA(1974) demonstrated inhibition of PVX in vivro and in vivi using C, Amaranticolor as a single lesion host. When allowed to preincubatable for 15-20 min, 44% and 63% inhibition of lesion formation was obtained using nimbin and nimbidin, respectively. With pretreatment of the test plan by spraying nimbin and nimbidin even better results were obtained, when the treatment was carried out 12 h or more before in oculation. The inhibitory effect of the treatments p.i. also increased with more time after the infection process and reached 43%(nimbin) and 35%(nimbidin) when carried out 24 h p.i. Unfortunately, VERMA did not mention which of the three concentrations used in the first test used to perform the pre- and post- inculation tests. A pre inculation root treatment for 24 h did not lead a reasonable inhibition when tomatoes were used, but with C. amaranticolor, local lesion formation was reduces using a mixture of nimbidin and nimbin at 250 ppm. Higher concentrations mostly resulted in phytotaxics reactions of both test plant species. Experiments by the author using aza resulted in high or low inhibition, but it was never significally different from with the methonal control, indicating the aza has no significant antiviral properties that the methonolic solution seems to be an inducer of resistance. Similar results were obtained with methonolic extracts of neem representing an earlier stage by the methonal control, but in some experiments higher concentrations of extracts tended to have stronger effects.
SEED OIL
In field experiments conducted in Tamil Nadu (India) 1% neem oil sprays reduced significantly ring mosaic disease of peanut caused by ToSWV. The effect of oil application seemed to be twofold; the incidence of the viral vector Frankliniella Schultzei was reduced and an antiviral activity was diagonosed under laboratory conditions. Unfortunaetly the numbers did not give the details of these laboratory experiments that "antiviral activity was measured by symptoms, When Vigna Sinensis was used as the indicator plant, neem oil completly inhibited lesion formation. A reduction in urd bean leaf crinkle infection in Vigna Mungo was demonstated by SABITHA and JEYARAJAN with sprays of neem oil(1% 5%) but it did not exceed 40% and it cannot be excluded that this effect was only due to an inhibition of the virus transmission i.e the vectors. As no further details were given, it remains unclear which of the crinkle viruses of the urd bean found in India is meant the ULCV transmitted by Henosepilachna Dodecastigma the applied transmissible virus or the whistlefly-transmissited virus. All three vector groups can be affected by neem, as discussed later. In experiments with ilarviruses and cucumbers, topical application of neem oil had no effect on the number of infected plants or severity of symptoms ROYCHOUDARY and JAIN gave a diffferent interpretation for their results with mechanical inoculations of different host species with TMV, saying that virus multiplication is inhibited by neem oil.
SEED OIL
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| Seed Oil |
In field experiments conducted in Tamil Nadu (India) 1% neem oil sprays reduced significantly ring mosaic disease of peanut caused by ToSWV. The effect of oil application seemed to be twofold; the incidence of the viral vector Frankliniella Schultzei was reduced and an antiviral activity was diagonosed under laboratory conditions. Unfortunaetly the numbers did not give the details of these laboratory experiments that "antiviral activity was measured by symptoms, When Vigna Sinensis was used as the indicator plant, neem oil completly inhibited lesion formation. A reduction in urd bean leaf crinkle infection in Vigna Mungo was demonstated by SABITHA and JEYARAJAN with sprays of neem oil(1% 5%) but it did not exceed 40% and it cannot be excluded that this effect was only due to an inhibition of the virus transmission i.e the vectors. As no further details were given, it remains unclear which of the crinkle viruses of the urd bean found in India is meant the ULCV transmitted by Henosepilachna Dodecastigma the applied transmissible virus or the whistlefly-transmissited virus. All three vector groups can be affected by neem, as discussed later. In experiments with ilarviruses and cucumbers, topical application of neem oil had no effect on the number of infected plants or severity of symptoms ROYCHOUDARY and JAIN gave a diffferent interpretation for their results with mechanical inoculations of different host species with TMV, saying that virus multiplication is inhibited by neem oil.
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