The San Antonio Sandbur Patch

[Wildcat82]

Over the past 3+ weeks none of my tomatoes have set any fruit, and only 2-3 plants out of 24 have grown at all despite nice temperatures. It looks to me like broad mites attacked my tomatoes during the 3 week period between late January when I planted out and later February when we had out last hard freezes. I never sprayed my tomatoes during this period - It’s baffling broad mites would be active in winter between hard freezes, but it is what it is. I don’t know how else to explain the hard stunting of my plants. Perhaps the bone dry conditions (1.5" rain in the past 4.5 months) here spurred on an extremely early mite outbreak. Hardest hit were all the dwarf-type plants: New Big Dwarf, Rosella Purple, Glacier. Two weeks ago I planted out several of my younger heat set varieties (Super Sioux and Juliet) but they are rather small and may not be big enough to withstand an onslaught of mites.

This is my third crop failure this spring.

Over the past few days I’ve raided the local nurseries for some additional bigger plants: Sungold (2) Juliet (1) Lemon Boy (1) Big Brandy (1), Arkansas Traveler (2) and Champion 2 (1). Since it appears we’re in the middle of a mite wildfire, I’ve decided to adopt a rather extreme spray schedule for my new tomatoes and recently planted okra, mulberry and figs as well as my pomegranates and dwarf peaches:

Mondays: Horticultural Oil
Tuesday: Venerate
Wednesday: Grandevo
Thursday: A rotation of Minx/Oberon/Pylon (Spectre)
Friday: Horticultural oil
Saturday: Rubbing alcohol/citric acid mix
Sunday: Rubbing alcohol/citric acid mix

But there is good news!!!!!
Over the last year, I’ve done a lot of research on mites and ever since Grok 3 came out in February, I’ve been doing more research. Grok3 verifies much of what I already gleaned from the scientific literature plus way more information. I have compiled probably 20 pages of conversations I’ve had with Grok3. Here’s the abbreviated Cliff’s Notes summary:

My Question: Do Woolly cultivars with wild introgressions (e.g., S. habrochaites crosses) have increased resistance to russet mites or broad mites. Give a percentage of how much their resistance is increased
Woolly cultivars with wild introgressions, such as those derived from Solanum habrochaites crosses, do exhibit increased resistance to russet mites (Aculops lycopersici) and broad mites (Polyphagotarsonemus latus) compared to standard cultivated tomatoes (Solanum lycopersicum). This resistance stems primarily from the higher density of glandular trichomes and the production of defensive compounds like acylsugars and sesquiterpenes, which are inherited from wild relatives. However, assigning an exact percentage increase in resistance is challenging due to the lack of specific, quantitative studies directly measuring russet or broad mite resistance in these cultivars. I’ll provide an informed estimate based on related research and explain the reasoning.

Estimating the Percentage Increase:
Without direct experimental data on Woolly cultivars (e.g., Woolly Kate) or specific S. habrochaites crosses against russet or broad mites, I’ll extrapolate from studies on similar pests and traits:
• Spider Mite Studies: Research on S. habrochaites introgression lines shows resistance to spider mites can reduce pest populations or damage by 50-90%, depending on trichome density and compound production (e.g., Simmons & Gurr, 2005; Alba et al., 2009). For instance, lines with high type IV trichome density often cut oviposition rates by 60-80%.
• Russet Mite Evidence: Anecdotal and indirect evidence from wild tomato trials suggests russet mite damage is reduced by at least 50% compared to susceptible cultivars, with some resistant lines showing damage levels dropping to 20-30% of what’s seen in S. lycopersicum (e.g., reduced bronzing and defoliation).
• Broad Mite Parallel: Broad mites, being similarly small and trichome-sensitive, likely experience comparable resistance, though their feeding behavior (curling leaves, stunting growth) might allow some persistence. Resistance likely falls in a similar range to russet mites.

My question: Do the following tomato varieties have an abundance of glandular type trichomes? Explicitly describe each variety: Woolly Kate, Woolly Blue Wine, Chinese Velvet (The original name is Kitayskiy Oksamitoviy, which means 'Chinese Velvet' in Ukrainian ), Scheherazade, Woolly Blue Jay, Churra Plum, Elberta Peach, Velvet Red, Furry Bumblebee, Roughwood Golden Tiger, Woolly Mammoth, Primary Colors, Angora, Fuzzy Wuzzy, yellow furry hog, and Extravagante Rouffiange. Estimate the amount oh S. habrochaites genetics

Summary Table
Variety/ Trichome Abundance/ Estimated S. habrochaites Genetics
Woolly Kate High 25–50%
Woolly Blue Wine High 25–50%
Chinese Velvet Moderate to High 10–25%
Scheherazade Moderate 30-50%
Woolly Blue Jay High 25–50%
Churra Plum Low to Moderate 0–10%
Elberta Peach Moderate 10–25%
Velvet Red Moderate to High 10–25%
Furry Bumblebee High 25–50%
Roughwood Golden Tiger Low to Moderate 0–10%
Woolly Mammoth High 25–50%
Primary Colors Low to Moderate 0–10%
Angora Moderate to High 25–50%
Fuzzy Wuzzy High 25–50%

Notes on Estimation
• Trichome Abundance: "High" indicates levels comparable to S. habrochaites (dense type VI glandular trichomes); "Moderate" suggests more than typical S. lycopersicum but less than woolly types; "Low" aligns with cultivated norms.
• Genetics Estimate: The Wo gene from S. habrochaites is dominant, so 25% wild genetics (e.g., F2 generation) could suffice for a woolly phenotype, though 50% (e.g., F1 hybrid) is common in initial crosses. Lower percentages reflect selective breeding to retain cultivated traits.
These conclusions are educated estimates based on naming conventions and tomato breeding patterns, as exact genetic data isn’t publicly available for most of these varieties. For precise trichome counts or genetic mapping, laboratory analysis would be required.



So it appears woolly mutants like Woolly Kate or woolly hybrids resulting from crosses S. Habrochaites) can confer mite resistance. The degree of mite resistance is likely variety dependent so some grow outs of woolly varieties would he helpful to compare.

In any event, a targeted spraying regimen probably should be initiated. And if you spray, the woolly types offer another huge advantage. Compare the sparse leaf canopy of the 4 foot tall Woolly Kate versus the thick monstrous leaf canopy of an 8 foot tall Black Cherry. The woollies are way easier to spray.

[leftylogan]

I scanned the entire grow log so I may have missed it but have you considered any integrated pest management options for mite control? i.e. mite predators from Arbico - https://www.arbico-organics.com/category/mite-predators

The commercial place I worked used Arbico products so I can vouch for them. I would run around with a bucket of thrips predators and toss the bran mix around ~15,000 square feet of greenhouse weekly. IPM isn't a cheap option by any means so fair warning. Combined with spraying it seemed to work pretty well (I don't remember what we were spraying). I review pesticide labels as part of my current job so I'll keep an eye out for mite products.

Amblyseius cucumeris is a good hot and dry option - https://www.arbico-organics.com/product ... eoseiulus/

[Wildcat82]

I scanned the entire grow log so I may have missed it but have you considered any integrated pest management options for mite control? i.e. mite predators from Arbico - https://www.arbico-organics.com/category/mite-predators

The commercial place I worked used Arbico products so I can vouch for them. I would run around with a bucket of thrips predators and toss the bran mix around ~15,000 square feet of greenhouse weekly. IPM isn't a cheap option by any means so fair warning. Combined with spraying it seemed to work pretty well (I don't remember what we were spraying). I review pesticide labels as part of my current job so I'll keep an eye out for mite products.

Amblyseius cucumeris is a good hot and dry option - https://www.arbico-organics.com/product ... eoseiulus/

Supposedly mite predators can be quite effective in greenhouse environments but anecdotally I've read they don't work well in an outdoor environment. If you've something that indicates otherwise, I would be interested.

[leftylogan]

Good sources are tough to come by still for IPM stuff. You're not wrong that efficacy is going to be lower in outdoor environments due to the increased variables. I will say the "greenhouses" I was applying it in were typically left wide open and with the sides rolled up 24/7 by the time we started regular applications and our retention rate was good.

Digging deep into my environmental science/ecology background back of tricks - as long as the predators have food they won't be looking to leave. The cucumeris don't fly so they have to move manually or hitch a ride to find new places for food. I was struggling to find anything talking about predators of the cucumeris but they're most similar to ticks. So the only predators of the cucumeris would theoretically be larger predatory bugs like wasps and spiders.

These look rather expensive but Amblyseius andersoni is a "pre-emergent" mite predator - http://arbico-organics.com/product/mite ... -predators. Combined with the cucumeris that's full life cycle and the spray regiment would fight off stragglers.

I looked through some of my product reviews and I see a ton of Abamectin products which also acts as a miticide if you're looking for another spray to add to the mix. I only went with the insects recommendation since it looks like you've tried a ton of other stuff over the course of a couple of seasons.

[Wildcat82]

Good sources are tough to come by still for IPM stuff. You're not wrong that efficacy is going to be lower in outdoor environments due to the increased variables. I will say the "greenhouses" I was applying it in were typically left wide open and with the sides rolled up 24/7 by the time we started regular applications and our retention rate was good.

Digging deep into my environmental science/ecology background back of tricks - as long as the predators have food they won't be looking to leave. The cucumeris don't fly so they have to move manually or hitch a ride to find new places for food. I was struggling to find anything talking about predators of the cucumeris but they're most similar to ticks. So the only predators of the cucumeris would theoretically be larger predatory bugs like wasps and spiders.

These look rather expensive but Amblyseius andersoni is a "pre-emergent" mite predator - http://arbico-organics.com/product/mite ... -predators. Combined with the cucumeris that's full life cycle and the spray regiment would fight off stragglers.

I looked through some of my product reviews and I see a ton of Abamectin products which also acts as a miticide if you're looking for another spray to add to the mix. I only went with the insects recommendation since it looks like you've tried a ton of other stuff over the course of a couple of seasons.

It gets confusing but abamectin is also sold as Minx (mentioned above) or Avid. Pylon is also sold as Spectre which I'm also using.

If I use the predatory mites, that means I have to forgo spraying miticides. I assume spraying would kill off the good guys buy maybe that's a bad assumption?

FYI - It's good to have an environment science/ecology guy on the board. I have a mechanical engineering background but in the Air Force I worked with a lot of Environmental engineers on remediation projects and EPA compliance matters.

[leftylogan]

Lost track of the conversation. Minx was of course the one product I didn't google before replying . I went through my work databases and I think you're covered on synthetic options. I'm digging through the biocide products as I have time. Have you ever put any powdered diatomaceous earth down to try and trash their exoskeletons?

I was thinking a two pronged attack even if the miticides kill the predators. Predators to reduce the population and the miticide to finish it off. This says that Amblyseius have decent resistance to neonicotinoid's (think active ingredients that end in prid) - https://www.sciencedirect.com/science/a ... 1318305086. Not a 1:1 to your products but it's a good sign.

I am an environmental scientist because of my interest in plants. My internet friends told me there's no money in plants so I went adjacent lol. All of my coworkers are engineers or geologists so I'm the odd one out but we're the ones receiving and reviewing those compliance reports . Always appreciative of those more mechanically inclined.