As per China Pesticide Registration Watch, to March 2019, the Chinese Ministry of Agriculture and Rural Affairs approved 418 pesticide registrations for use on watermelon. In terms of variety, the registered products are mainly fungicides, numbering 357 and accounting for some 85% of total.
There are fewer registrations of insecticides, herbicides and plant regulators, with 44 herbicides accounting for 11% of total, nine insecticides accounting for 2%, and eight plant growth regulators and others accounting for about 2%.
With regards to the targets of control, downy mildew and gray mold are the only two diseases not covered. All other diseases are covered by the registrations, with insecticides mostly targeting aphids, but there are fewer product choices for other common insect pests. There are also no products for controlling some watermelon pests, such as tetranychus cucurbitae, melon borer and spodoptera litura.
In China, there are 83 types of active ingredients registered for use on watermelon. The major registered active ingredients include difenoconazole, azoxystrobin, mancozeb, thiram and hymexazol. The mixtures are relatively unilateral, as shown in Table 1. There are more off-patent active ingredient registrations and less novel active ingredient registrations. Herbicides for use on watermelon mainly contain seven active ingredients, which are S-metolachlor, haloxyfop-P, napropamide, quizalofop-p-ethyl, metolachlor and butralin, with all having single agents. There are also no registrations of mixture formulations, therefore, products available for selection are quite limited. There are only two active ingredients registered for plant growth regulators, namely forchlorfenuron and brassinolide. Recently, the new active ingredients registered for use on watermelon are mostly biological agents, including Bacillus polymyxa and Bacillus amyloliquefaciens.
Table 1 Main Active Ingredients Registered for Use in Watermelon
Concerning the issue of toxicity, highly toxic products have been removed from watermelon applications. At present, most products are low-toxic, including 364 such products accounting for 87% of total registrations, 26 micro-toxic products accounting for 6%, and 28 medium-toxic products accounting for 7%.
The watermelon-oriented product regulations are mostly WP, SC, WDG and EC, as shown in Table 2.
Table2 Main Watermelon-oriented Pesticide Formulations