We're finally getting some breathing space. We've been uber busy prepping for winter, and, not that we're done, but most of the plants have been cut-back and/or divided and/or root pruned and/or fed, burped, diapered and put down for a long nap. There are an exuberant few still blooming despite some freezing nights--the diascia (twinspur) just doesn't know when to quit!. The plumbago and geraniums have colored up beautifully. Ahh, fall!
Last season convinced us that we can't control all our pests with a squirt of soapy water; though that works fine in our home gardens, working with thousands of plants in greenhouses has changed the equation. We have created a monoculture situation (albeit with lots of different plants) and monocultures draw bugs.Aphids love columbines--and we have lots of columbines!
We want to see spring come in with lovely, soft new growth, tender, succulent new growth--and no diners! So we're introducing some new predators to the propagation greenhouses. Encarsia formosa is a tiny wasp that parasitizes the eggs of whitefly. They come on a little white card that clips to the plant--very tidy looking.
For mites, we put down phytoseiulus persimilis, a predator that eats eggs, nymphs, and adults.
Fungus gnats are unavoidable in an organic greenhouse. They love warm, moist, organic mediums, and the larva eat roots. We struggle with our seedlings especially. There are a number of natural controls; we mixed beneficial nematodes in water, and have used it on all our new plantings. They eat other nasties too, like the larvae of fleas, webworms and others.
We're trying a new product made from sugars to knock down infestations. SucraShield. There doesn't seem to be any resistance to it: kills on contact.