Potential Pests in #NoPlant19

It seems a bit cruel to point out some potential pest issues in a season like we have had where few crops are even in and might not even get in. But some crops are in the ground and at risk. There are a few pests that will take advantage of delayed crop emergence or be so limited in what they find that those fields see heavier than usual infestations.

black cutworm cutting corn plant off
Black cutworm larva and corn seedling plant cut off at soil line. Jocelyn Smith, UGRC

Black cutworm in particular is something to be watching for. Black cutworm moth flights have been heavier than usual this spring. Moths easily found chickweed and low lying weeds to lay eggs on given how delayed herbicide applications have been. Fields that did get planted have young corn plants just emerging and there will be larger older larvae moving to them. These larger larvae can cut the tiny plants off at or below the soil level. More information on black cutworm scouting can be found in this previous Black Cutworm Article. Hybrids containing Cry1F or Vip3A traits (link to Bt trait table) or treated with Fortenza, Lumivia or Poncho/NipsIT insecticide seed treatment would be protected. Those fields without protection may still be able to have a rescue treatment done if the larvae are still smaller than 2.5cm in size. Anything larger and the insecticide will not be effective. For thresholds and rescue treatment options see the Field Crop Protection Guide.

Wireworms, millipedes, slugs and grubs take advantage of cool, wet springs like this. Crop emergence gets delayed and seeds and seedlings struggle to grow past the feeding injury. On the positive side, the later a field gets planted, the more likely the crop will grow quickly and avoid being fed on compared to those that got planted early.

Cereal leaf beetle (CLB) is another potential threat. CLB infestations have been reported today in Essex County but with so few acres of wheat across the province, any field is at potential risk. And heavier infestations usually follow cool, wet springs that seem to be detrimental to their natural enemies. More info on CLB can be found in this past Cereal Leaf Beetle article.

Alfalfa weevil is another pest to watch for. Similar to cereal leaf beetle, in cool, wet springs, their natural enemies don’t do as well. Delayed first cut can lead to significant feeding damage going unnoticed. More info on alfalfa weevil can be found in this past Alfalfa Weevil article.