Travelling the country side yesterday, I saw too much spider mite damage going out of control in soybean fields that were easy to spot from my car. Too many fields that still have some time to mature are seeing sure signs of spider mite activity. Some are already too late to control, as the mites have already started to kill off the plants (picture provided). But some are still at a stage of infestation that could make a world of difference if they were sprayed.
Spider mites are very hard on the soybean plant. Their feeding eventually causes the plant to drop its leaves and prematurly die. When infestations first start, individual leaves begin to look sandblasted or “dusty” on the underside of the leaf. Infested plants start to take on a grey appearance in patches in the field. If the infestation is allowed to continue, these patches eventually turn brown as leaves drop off the plant and the plants shut down and die.
Dimethoate (Cygon and Lagon) is the only product that will work on spider mites. Do NOT use Matador as it does NOT control spider mites and can actually cause the mite population to build up more quickly. However, the days to harvest interval for the dimethoate products is 30 days so if spider mites are active in your field, control will need to take place in the next week or two.