By: Ayman Mostafa
Talking with PCA’s, I found them using different techniques to deal with aphid populations in alfalfa. Some of them had aphids approaching the economic threshold level in their fields, so they decided to cut the hay a little early instead of applying an insecticide. Others had fields that were at threshold long before harvest and decided to apply a treatment. Another situation is the occurrence of higher populations of beneficials, which may make it possible to hold off spraying with the expectation that predation will keep aphids in check. Some folks go with the approach of pre-spraying, shortly after cutting. Whatever approach you take, everyone must adhere to the label limits for these products and active ingredients. For example, the specific use restrictions on Lorsban® Advanced label for alfalfa stated that “Do not make more than four applications of Lorsban Advanced or other products containing chlorpyrifos per season or apply any product containing chlorpyrifos more than once per alfalfa cutting.”
Conditions have been favorable for aphids to build up their populations in many areas of the low desert region. Our friends to the west in California also face high levels of blue alfalfa aphid. Similar to their observations, we are finding the heaviest densities to be very localized.
Efficacy trials for several aphicides are currently being conducted in the lower elevation desert in Arizona and California.
The Western Farm Press has this article about the current situation of aphids in alfalfa. Click Here to read this article.
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