There have been some reports of alfalfa weevil causing damage in some stands and I was out this week to have a look at some fields. The weevils are certainly out there. Considering that some alfalfa fields are hurting from frost damage, some produces may consider holding off on the first cut to let the plants build up more reserves in the crown. Typically, cutting is a good method of control and is done before weevil populations get too high. If the stand needs to be left longer, then monitoring for weevil populations should be done to determine if treatment thresholds are reached prior to cutting especially in fields with a history of alfalfa weevil damage.
Scouting for Weevil
If there is 40% leaf-tip feeding, with 2 or 3 active weevils per stem and there is more than 7-10 days to preferred harvest date, consider applying an insecticide. If you find less then 1 active larvae per stem no treatment is needed but keep monitoring the situation. Action will be required if you find two larvae per stem and the alfalfa is less then 40 cm high. If you find more than 3 larvae per stem, immediate action is needed. For more information see check out the following link: http://www.omafra.gov.on.ca/english/crops/pub812/3weevil.htm
There are some reports of true armyworm catches in Illinois and Pennsylvania so it looks like we should be seeing some adults soon if they are not already here. Considering the weather conditions we’ve had this spring, it might be a good idea to start scouting for this pest soon. More information on true army worm and scouting techniques can be found at: http://www.omafra.gov.on.ca/english/crops/pub811/13cereal.htm#tarmyworm
If the corn is up, it is time to start scouting for black cutworm!