What can I do to control root knot nematode in my hoop house that grows lisianthus for a cut-flower market?

Answer: You’re probably farming on sandy soil, which nematodes very much enjoy. I’m guessing that you grow lisianthus flowers pretty much year after year in your hoop house. That is also something which the nematodes would very much enjoy. I try to stress to growers that I work with that it’s important to think about the soil as a complex ecosystem, which has certain requirements. That means rotating your crops, and it also means you should consider adding organic matter back into the soil every year. Crop rotation diversifies the soil environment through the different chemicals that the plants exude through their roots. It also avoids growing a plant every year that is a host to a particular pest. If you’ve grown lisianthus several seasons in the hoop house, then you’ll likely have a pretty healthy population of root knot nematodes, even though lisianthus is relatively resistant to them. So, one thing I would suggest is to plant something that is not a host to root knot nematodes.A healthy soil hosts a very diverse soil ecology. Regular additions of organic matter, through the use of compost, cover crops, and plant residues, supports a healthy soil ecology where there are many checks and balances to keep pest populations from getting out of hand. Good-quality compost is likely the most practical method of adding organic matter to your hoop house soil (I’m assuming the lisianthus are “in-ground” and not on benches). The compost will also help your sandy soil retain nutrients and water much better than sandy soil without compost. To learn more about cut flower production, consult the ATTRA publication Specialty Cut Flower Production and Marketing. You’ll also find additional useful resources on our Soils & Compost page.