Application of neem seed extracts in the controlling of insect pests of Chinese kale on farmer's field

Efficacy of different neem seed extracts on some insect pests of Chinese kale was conducted on the farmer's field at Pathumthani province. The experiment was designed in randomized complete block with plots of 3.5 * 3 square m. Each treatment is replicated three times. The first spray of neem extracts and insecticide commenced on about the 15th day after sowing and continued once every 5 days until 7 days before harvesting. In the first trial, various neem seed extracts as alcohol, aqueous, Nlm and soxhlet extracts were compared with the conventional insecticide as Bacillus thuringiensis (Florbac) plus methamidophos. All tested neem formulations were effective as the same as insecticide to control Spodoptera litura and Hellula undalis larvae, but alc. extract 5 percent and Nlm 5 percent could lower the population of Plutella xylostella better than the other neem formulations including insecticide. Yield of plants treated with neem extracts and insecticide showed no statistical difference. The second trial was the comparison of alc. neem seed extract 5 percent with the mixture of alc. neem seed extract 3 percent + galanga 1 percent + lemon grass 1 percent and the commercial neem-based insecticide "Advantage" (the mixture of neem seed, galanga and lemon grass). Alc. neem extract 5 percent gave the best result than the other treatments to control S. litura, and H. undalis larvae but showed no statistical difference to control P. xylostella. Yield of Chinese kale in plots treated with alc. neem extract 5 percent gave the highest marketable quality with statistical difference than the others. The last experiment was the comparison of alc. neem seed extract 5 percent with alc. neem seed extracts in paste form and B. thuringiensis "Argona" plus carbosulfan. Alc. neem extract 5 percent and neem extracts in paste form at 0.25 and 0.5 percent showed the same effective as insecticide. The highest marketable yield was shown in plots treated with alc. neem extract 5 percent followed by neem extract 0.25 percent + neem oil and neem seed extract 0.5 percent and insecticide respectively.