cross-posted from: https://lemmy.world/post/17588319
[Image description: a thicc green hornworm hanging onto the stem of a tomato plant. The hornworm is speckled with little white dots, has eyespots and angular white stripes down his side, and the namesake sharp little spike of a horn on its butt.]
I wish that they were the biggest problem bug for my tomatoes, but that title goes to the godforsaken spider mites. They decimate my plants every summer as soon as the weather turns hot, and I've tried so many things to combat them.
This year I've applied a couple rounds of predator mites, and in addition to some ruthless pruning of affected plants, I feel like I'm actually holding ground in the battle. Though really hoping that the predator mites will establish a population, as they're a pricy solution.
Predator mites work best on corn (they eat the pollen) and in the greenhouse. As you've noticed when it gets hot they don't do as well.
Stethorus punctillum work for when it gets hot.
Yeah, would be nice if I were in a closed environment and could keep them from running away!
I've tried neoseiulus californicus and galendromus occidentalis, and also zelus renardii as a generalist predator. I've considered stethorus punctillum, might have to give them a shot too.
Putting out the assassin bugs with the predatory mites is not a good idea. They are indescriminate hunters. They also tend to fly away. They do a better job on aphids and whiteflies in my experience.
The G. occidentalis usually only works in cooler temps below 90F. Above that their populations crash. They are awesome in a temperature controlled greenhouse.
N. californicus can take the heat but need high levels. This is why they work in corn. Apply them at tasselling and they reproduce on the corn pollen rapidly. They then can suppress spider mites for the rest of the season. Otherwise you are left releasing every 2 weeks for the rest of the season. It works but it's expensive.
That's a fair point, didn't consider that my generalists would probably also be happy snacking on my good guys. I released them along with the G. occidentalis back in May when it was much cooler, in the hopes of preempting the spider mite spread.
The N. californicus I released in mid June, and though I didn't happen to grow any corn in the garden this year, hopefully the volume of spider mites is enough to keep them well fed.
Is safers soap something you would be interested in maybe using? It’s safe on vegetables after washing them.
Yep, I've tried various soaps and all kinds of oils, tried regularly spraying down the leaves to keep them dust free and the humidity up, tried removing plants at the first sign of infestation, all of it seemingly futile under the literal avalanche of mites I get every summer. If I miss a few days of these preventative measures, my poor tomatoes will have leaves gone from a slight sign of damage to a fully webbed death. And it's not like my plants are water starved either, I use drip irrigation under thick mulch, so the soil stays moist even on the hottest days.
It's been really constraining on my growing season. I'm often able to get plants in the ground around mid-February and get a good harvest in May, but June/July is spent just watching all my plants die a lingering infested death. I'm in 10a, so I should easily be able to get a second summer crop in, but new seedlings planted at the end of spring seem to fare even worse than their established brethren. Hence why I've finally decided to spend the $$$ on predators, really hoping that their population establishes and tames the micro menace.
Shit that’s rough, is it localized to just you? Or do your neighbors get it as well?
Hard to judge, as not one of my next door neighbors is interested in gardening, despite my efforts at offering seeds/seedlings/help.
I haven't gotten to really connect with any gardening groups in my area, but the handful of folks I have talked to also have problems with spider mites, though not sure if to quite such a severe degree.
Hrmm I’ve heard skipping a season if they’re really bad can be a potential solution, I know it’s tough to not plant anything, but if it’s one year and it makes the rest better instead of a constant struggle. Maybe worth a try?
Yeah... the thought has crossed my mind, even though tomatoes are my absolute favorite thing to grow. If I knew for sure it'd really reduce the population, I could probably convince myself, but how sad would it be to have a tomatoless year just to have the mites back in full force the next. 😕
Grow indoors one year? You probably spend close to the same amount in remediation as you could get a light and a tent if the light bleeds an issue.
I’ve experimented with some veggies in my aeroponics system, but soil works too.
My understanding is the point is to make them want to go somewhere else and nest for the winter or whatever they do. They stay since they know they get fed every year.