Tomato Teachings: Lessons from Eight Summers of Field Research

For some gardeners, growing tomatoes is a breeze. I am not one of them. As of August 2025, I had two tomato plants at home. One of them was thriving, despite almost dying from a week without water at the end of July; I had planted it in a large container, and it looked great, with dark green new growth and plenty of those bright yellow flowers, but no developing fruit. “That’s okay,” I thought. “Maybe she’s a late bloomer. I’ll give her more time before my final judgment.”

Meanwhile, my other tomato plant had been watered consistently and was technically still alive. At 7 inches by mid-August, it was shorter than when I transplanted it into the ground in early June. In contrast, a few of the neighboring plants, like butterfly bush and lamb’s ears, were living their best lives. No signs of water stress. So, I didn’t think it was a water issue. Not sure what the problem might have been.

By late October, I’d given up on both. Another homegrown tomato season bites the dust.

In another realm, just 3.5 miles away, the more than 20,000 lbs. of tomatoes grown for my summer research projects over the past 8 years are a whole other story. I work in Los Lunas at one of NMSU’s Agricultural Science Centers—a research farm that’s constantly abuzz with projects involving all sorts of crops (e.g., alfalfa, beans, chiles, grapes, jujubes, melons, tomatoes, various cover crops, and more). This is my 8th summer studying tomatoes, and I’m still learning. We harvested over 5,000 lbs. of tomatoes in 2021, over 3,000 in 2023, over 6,000 in 2024, and we were expecting another fruitful year in 2025. 

In past summers, we had focused on the effects of different types of shade (like 15% and 50% white shade cloths) and different irrigation methods on disease prevalence and fruit yield.  Our long-term goal was to study and demonstrate ways to sustainably grow healthier, more productive, resilient tomatoes in our tough climate. 

The plot thickens.

In 2025, together with our crew, volunteers, and interns, we planted tomatoes for a New Mexico Department of Agriculture-funded study on how shade from solar panels might affect tomato diseases, such as the blasted beet curly top virus. Growing crops under solar panels is called “agrivoltaics.” We were looking at the differences between tomato plants grown under periodic shade and those grown in full sun.

Beet curly top virus (aka curly top or BCTV) is transmitted by a little insect called the beet leafhopper. They’re shaped like a grain of rice, but smaller. Research has shown that these tiny critters prefer to feed in full sun, so the shade provided by solar panels may act as a deterrent.   

Of the 140 study plants, by late October 2025, we had only 23 left and even a few of those were looking piqued. 

Throughout the summer, we sent leaf samples to the Plant Diagnostic Clinic on NMSU’s main campus in Las Cruces for help determining what was going on. The NMSU Plant Diagnostic Clinic (https://plantclinic.nmsu.edu/) accepts plant samples for identification and disease testing, plus insect identification. If you submit samples via your County Extension Agent, the diagnostic services are free! Find your County Cooperative Extension office here: https://extension.nmsu.edu/county.html 

Disease. That’s what we found. And not just one. 2025 diagnoses included beet curly top virus, tomato spotted wilt virus, cucumber mosaic virus, and early blight (aka Alternaria fungus). If you think you’re battling one (or several) of these diseases, check out https://bernalilloextension.nmsu.edu/yardgarden/tomatoes.html for details on these common culprits. 

This year, even though we lost over 83% of our study plants, we still harvested over 1,000 lbs. of tomatoes. The plants that survived really held their own and produced well, thankfully.

Next year we’ll be studying the effects of various shade cloth strengths. If all of this trial and error doesn’t scare you, you are more than welcome to join in the fun!

If you’re interested in learning more about our 2026 tomato studies starting up in Los Lunas this May, find details about volunteering and attending workshops here: https://nmsudesertblooms.blogspot.com/p/events-volunteer-opportunities.html.

By Marisa Thompson, PhD, NMSU Urban Horticulture Extension Specialist