Looking forward to another growing season.  This spring started off with some pretty warm weather a couple of weeks ago and things started to move forward with insects becoming active and plant buds pushing out. With the colder temperatures that have been following, insect activity has somewhat slowed down and we should still be vigilant for our spring insects, especially those that are feeding on developing buds. Flea beetle and cutworms are the main insects to pay close attention to right now as they can hollow out grape buds as the buds are swelling. Thus, carefully monitoring should be implemented at this time. As we discussed in previous years, the injury caused by both flea beetle and cutworms look the same: they hollow out developing buds when feeding on them. This injury occurs from bud swell to ½ inch shoot growth. Once the buds have reached ½ inch shoot growth, the injury occurs on leaf tissue and is no longer cause for concern.

While the damage symptoms look similar, it is important to determine what insect is responsible for the damage as control measures differ depending on which pest is present in your vineyard (table below). For more detailed information about these insects, please refer to this previous article or to this Bud Swell Webinar recording. At this time, it is important to know that cooler temperatures in the spring tend to prolong the bud swell stage which provides a longer period of feeding activity for flea beetle and cutworms. Please see below for the timing of activity, scouting methods, thresholds, and management strategies for these pests.

	Cutworms	Flea Beetle
Appearance	Credit	R. Bessin, University of Kentucky
Insect species	Multiple species of cutworms (Noctuidae) main species being spotted cutworm (Amathes c-nigrum)	Altic chalybea
Timing of activity	Larval feeding at night	Adult feeding during day
Scouting	Scout at night on plants or during the day digging top soil around the plants	Scout during the day on plants
Developmental stage affected	Bud swell through bud break	Bud swell through bud break
Where they may be most prevalent	Sandy soils, weedy areas	Near forested edges
Cultural control	Removing weeds, leaving some extra buds when pruning	Removing brushy overwintering sites for beetles at vineyard edges
Action threshold	2-4% bud damage	2-4% bud damage
Some chemical controls OMRI approved	Altacor, Belt, Brigade, Delegate, Lorsban, Baythroid, Danitol, Sevin  Entrust, DiPel, Pyganic,	Baythroid, Danitol, Sevin, Imidan, Renounce, Scorpion Pyganic

For more chemical control recommendations, please refer to the Midwest Spray Guide. Please note some overlap in insecticide options between insect groups. The label is the law, please follow the label!

Some more considerations on chemical control include research from Washington State suggesting to apply a pyrethroid trunk spray to control cutworms as they climb up the trunks to feed on buds.

Happy growing season!

This article was posted in Grapes, Insects and tagged Christelle Guédot, cutworm, flea beetle, grape bud swell, Grape Flea Beetle, Grapes, insects.