Significant infestations of spider mites, particularly in dry years, can cause leaves to turn yellow, then gray-green, and finally bronze. Observe plants closely and with a handlense to see the tiny mites crawling on the plant, or look for dense webbing and presence of frass (black spots) in the webbing.
Mite problems typically develop near gravel roads (where road dust coats leaf surfaces), or downwind of newly swathed alfalfa fields or mowed roadside right-of-ways, which can serve as emigrating sources of mites.
Look closely at plants with a handlense.
Plants losing more than 50 percent of their foliage during bloom and pod set may warrant treatment if significant pod or seed filling remains and leaves have not yellowed. The
use of drop nozzles may enhance control by improving coverage of the undersides of leaves. Complete control is difficult to achieve.
None listed.
|
Insecticide |
Rate |
|
Chloropyrifos (numerous products) |
Check label, but generally 1 pint/acre |
|
Chloropyrifos plus gamma-cyhalothrin (Cobalt) |
See label, 13 to 26 fl. oz./acre |
|
Dimethoate (Dimethoate 2.67EC) |
1 1/3- 1 1/2 pts (.4-.5 lb. ai.)/acre |
|
Lambda-cyhalothrin chlorantraniliprole (Besiege) |
10.0 fl. oz./acre |
|
Zeta-cypermethrin plus bifenthrin (Hero) |
10.3 fl. oz. of product/acre |