Soybean Aphid Colonies Found on Buckthorn this Week

Scouting efforts by industry reps and my students have verified that soybean aphids have started to emerge on buckthorn. Colonies were found on buckthorn leaves at a few of our known buckthorn sites last week though the colonies were a bit smaller then previous years. This is the more normal time for aphids to be emerging on buckthorn, unlike last year when the aphids were brought in very early from other regions and landed on soybeans immediately in early May. And because of the delay in crop emergence, we have been able to avoid a May infestation on soybeans this year. Typically Ontario experiences the start of SBA colonies on soybeans by around the second week of June. These of course tend not to reach threshold in June, unlike last year, but instead slowly increase in fields and migrate to later planted fields in July when they then may reach threshold depending on crop conditions and natural enemy activity.

Early planted fields deserve at least one scouting trip by late June to make sure that aphids are not reaching thresholds in the field. And all fields should be scouting on a weekly basis from July until September to ensure that infestations do not sneak in and reach threshold without you knowing about it.

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