Development of a reduced use pesticide program for the sustainable management of disease, insect and weed on Chinese Kale production

Epidemiology of pest complexes is one of the most serious problems affecting Chinese Kale production in Thailand. Pest management in this vegetable crop traditionally has been accomplished through pesticide application that pose the risk of developing resistance and environmental concerns. Field trial was conducted during March-May 2008 at Suphanburi production area to determine the effects of biocontrol agents and products in combination with cultural practices on the incidence of Alternaria leaf spot (caused by A. brassicae) and insect pest and weed population. Reduced pesticide programs comprising combinations of Pseudomonas fluorescens SP007s powder formulation (for disease control); Bacillus thuringiensis, Non-taai-yaak extract: Stemona collinsea, and natural enemy including stink bug: Eocanthecona furcellata and earwigs: Proreus similans stallen (for control of insect pest); and hoe weeding and straw mulching (for weed control) were investigated. Additional programs with alachlor herbicide, all alone pesticides (alachlor, copper hydroxide, abamectin, mancozeb), conventional practices (mentioned pesticides and swine placenta extract plus EM), and nontreated control were included in the experiment. Reduced pesticide programs provided adequate levels of disease, insect and weed management compared with nontreated control. Although the programs did not clearly affect the abundance of weed populations, there were program differences in the incidence of disease and insect pests. When one of reduced pesticide program (5-non-taai-yaak and 3-P. fluorescens SP007s foliar spray intervals) combined with alachlor herbicide, it significantly reduced alternaria leaf spot, insect pests (Phyllotreta flexuosa and Spodoptera litura except Plutella xylostella), and weed population (broad leaf and early season grass) and increased yield compared to all alone pesticide and conventional programs. In this study, reduced pesticide programs comprised of stink bug and earwigs; and hoe weeding clearly reduced P. xylostella; and grass weed, respectively. These reduced pesticide programs appear to be a promising strategy for pest management of Chinese Kale production and could minimize grower reliance a conventional pesticide application.