Pests - 71
 

 

 

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WATER WEEVIL HABITS NOW BETTER KNOWN

New findings indicate that water weevils during spring flights choose areas next to levees, particularly field comers. This suggests that management of levee cover, proportion of levees to fields, and paddy shapes may influence the level of infestation. The weevil is found to feed on 21 host plants, most of which are weeds, and prefers water grass to all other weeds tested.

WATER WEEVIL CONTROL BY CHEMICALS

Carbofuran will likely be available for a postplant treatment to drained fields in the event that an infestation develops and a preplant treatment was not made. This use is dependent upon state clearance, and a supplement to the '72 Pest and Disease Control Guide will be distributed if it is approved. An application for a tolerance and the registration of Bux for weevil control has been submitted, but approval is not expected to be in time for this season.

SEEKING RESISTANCE TO WATER WEEVIL

Over 3,000 lines investigated revealed 38 with less than average root in. jury and 6 with only slight injury.

CONTROL OF WATER WEEVIL BY WATER MANAGEMENT

Even though water management promises some control of water weevil, problems may ensue in fertilizer loss, weed control, and ways of managing water rather quickly. A recent test showed that draining at 10 days, 2 months, and 3 months changed yields but little from continuous flooding with additional fertilizer added before reflooding.

RESIDUE MANAGEMENT AFFECTS PESTS BUT LITTLE

Whatever the residue management followed, Aedes mosquitoes, oligochaete worms, and midge populations seemed unaffected; water weevil differed little between burned and incorporated paddies treated preplant with Bux and carbofuran; burning levee grasses left over-wintering weevils unaffected; tadpole shrimp were found in flamed and unflamed soils.

HERBICIDES CONSIDERED FOR REGISTRATION

Data from developmental work with Hydrothol 191 and Bolero is being used to support industry petitions for federal registration. If registered, Hydrothol 191 will control American pondweed, and Bolero will be the first commercial herbicide that will control sprangletop, ducksalad, and barnyardgrass at reasonable rates. Growers are advised that soil incorporation inactivates Bolero.

 

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