The widespread use of black polythene mulches and other cultural practices in strawberry production provide favorable conditions for black vine weevil survival and development. Nematodes have been successfully used to control black vine weevils in potted plants and greenhouse crops, and would be especially useful in strawberries where insecticides cannot be applied close to harvest.
In field experiments in England, a commonly used drip irrigation system (T-Tape®) was evaluated as a practical and inexpensive method of application to deliver nematodes in the root zone, where the larvae feed. The tape(s) ran along the bed, between the two rows in the double row raised beds, about ½ inch deep in the soil, with outlets about every 1¼ (one tape system) or 1½ inches (double tape system). The double line system performed better than the single line system, effectively distributing the nematodes along and across raised beds and placing them close to the root zone.
Nematode applications were aimed at late instar larvae during spring (once the soil temperature is warm enough), and early instar larvae during summer. Late summer field applications with Steinernema carpocapsae caused only 49.5% reduction in the early instar larvae, while applications in later spring resulted in 65% control of late instar larvae. Heterorhabditis megidis was not as effective against late instar black vine weevils.
In strawberry or other crop systems where drip irrigation is used, S. carpocapsae could be applied inundatively twice a year (late spring/early summer and late summer/ early fall) as part of a routine irrigation procedure to keep black vine weevil populations below the economic threshold. Applying the nematodes in an irrigation system makes it easy to regulate the amount of water in which the nematodes are applied.
Kakouli-Duarte, T., L. Labuschagne and N. G. M. Hague. 1997. Biological control of the black vine weevil, Otiorhynchus sulcatus with entomopathogenic nematodes. Ann. Appl. Biol. 131: 011-027.
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