Knowledgebase

spots on collard green leaves #879238

Asked July 29, 2024, 12:56 PM EDT

Hi, My collard greens, growing in a little greenhouse, are developing small white spots on the leaves. Otherwise, they seem very healthy. The spots show up on older leaves, new growth in the center starts out spot-free. Can you tell me what is causing these spots, if they are harmful, and how I can prevent them? Thank you!

Wayne County Michigan

Expert Response

This looks like damage from thrips (Thysanoptera). Thrips are small insects that are a common pest in greenhouses and other indoor growing spaces in Michigan. There is no one-size-fits-all approach to thrips management in greenhouses. I would recommend starting by using sticky cards (yellow or blue), to measure the population and determine where they are in their life cycle. There are effective biological controls for thrips, but they tend to work best when thrips populations are low. You can read more about thrips biological control in this article from MSU Extension: https://www.canr.msu.edu/news/timing_the_release_of_beneficials_is_critical_to_biocontrol_success

An Ask Extension Expert Replied July 30, 2024, 10:33 AM EDT

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