5.1.22
A NOVEL METHOD TO HOLD APHIDS AT BAY

V KURUCHEVE, V RAVICHANDRAN and K ANANDH

Department of Plant Pathology, Faculty of Agriculture, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu, India

Background and objectives
At present, there are no chemicals that can be used commercially to cure crops of virus infection. Over 70% of all insect vectors of plant viruses belong to the order Homoptera and the aphids are the most important vectors of this group. Spraying animal dung extracts completely protected blackgram (Vigna mungo) plants from aphid (Aphis craccivora) colonization [1]. In the present investigation, the effect of fresh animal dung was tested with some more pulse crops and the results are reported.

Materials and methods
One pot trial was conducted with blackgram, greengram (Vigna radiata) and cowpea (Vigna unguiculata) by following the method in [1]. Fresh animal dungs (10%) were sprayed twice a week for 2 months starting from seedling emergence. Dithane M-45 (0.25%) and monocrotophos (0.025%) was sprayed three times at 15 day intervals for comparison. Each treatment was replicated six times. Total aphid colony was counted just before harvest. Yield parameters were also recorded.

Results and conclusions
In animal dung- and monocrotophos-sprayed plants there was no single aphid colony found, whereas in control and dithane M-45 treatments aphid numbers were 2345 and 1825, respectively, per plant. Non-colonization of aphids in animal dung-sprayed plants may be due to repellent or antifeedant activity, and this result once again confirms our earlier findings [1]. Several reports are available pertaining to the use of plant products in managing the insect vectors but not with animal dung. Buffalo (Babulus bubalis) urine was reported to possess fungitoxicity [2] against Macrophomina phaseolina, thus suggesting the pesticidal value of animal excreta. All the treatments increased the yield parameters significantly when compared to control. Among them, monocrotophos treatment recorded the maximum effect followed by cow plus goat dung (10:1) extract. Thus, animal dung offers a safer and practical pesticide for managing the aphids in pulses.

References
1. Kurucheve V, Murugesan R, Sundarraj T, Ravichandran V, 1997. Proceedings of the Indian Phytopathological Society International Conference: Integrated Plant Disease Management for Sustainable Agriculture, Abstract, pp. 199.
2. Raja J, Kurucheve V, 1997. Plant Disease Research 12, 11-14.