As a pre-emptive starting note, there are a lot of questions with similar titles but none I could find with pictures looking the same to what I have here.
Around a week ago, I applied lawn clippings to the surface of the soil in my greenhouse as a mulch. The soil was previously free of visible weeds or other pests and I'm aware that I may have made a mistake in introducing non composted grass clippings.
Today I noticed hundreds of small white balls that have appeared in several areas. They seem to be either eggs or some type of fungus. The fact that they appear to be "growing / deposited" on a plastic plant label makes me think that fungus is less likely, as I'm not sure that it would grow on a plastic.
In one picture a strawberry plant appears to be attacked.
- What are these balls?
- Are they harmful to my plants?
- If so, how should I deal with them and what precautions can I take in the future?