|
The beet armyworm, Spodoptera exigua, (BAW) is a major pest of leafy vegetables
grown in the desert southwest. Typically, BAW populations begin infesting newly
planted fields soon after plants emerge in early September and can remain heavy
through early November under favorable weather conditions. Fortunately for local
PCAs, several insecticide alternatives are available that provide excellent residual
activity on this pest. Furthermore, many of the products have different modes of
action (MOA) that can be alternated throughout the growing season. Thus the rapid
development of resistance by BAW to any of these insecticide compounds should not
readily occur. However, if an insecticide compound, or products with the same MOA,
are used repeatedly for BAW control in the same field, the risk of resistance increases
significantly. This is particularly important with the Diamide group of insecticides
(IRAC group 28) because these products can be applied as both foliar sprays and
soil injections, and because there are currently six Diamide products labeled in
leafy vegetables with the same MOA (Coragen, Durivo, Voliam Xpress, Voliam Flexi,
Synapse and Vetica). Applying these Diamide products to the soil at planting, and
applying them as foliar sprays in the same field, can expose multiple generations
of BAW to the same MOA. That’s not a good way to use these products if you want
them to remain effective for more than a couple of years. Since the Diamides, as
well as the other products currently available (Radiant, Proclaim, Intrepid, Avaunt),
are critical to effective management of BAW and other Leps in leafy vegetables,
PCAs should consciously avoid the overuse of any of these compounds. The most effective
way to delay the onset of resistance by BAW in leafy vegetables is to consider the
recommendations provided in the guidelines recently prepared entitled
Insecticide Resistance Management Guidelines for Beet Armyworm in Lettuce.
To contact John Palumbo go to: jpalumbo@ag.arizona.edup>
|
