For me, the Napa County Master Gardener tomato sale elicits heavenly thoughts of tastes to come. I adore tomatoes. My husband once planted 18 plants for the two of us. I used every tomato—either by eating, cooking, dehydrating or freezing them. We have home-grown tomatoes year-round.
At the end of the season, I put the remaining vines of green tomatoes in a paper bag in a cool, dark space. They continue to ripen. We have eaten fresh tomatoes this way into January.
Thank you to all who attended the Master Gardener tomato sale on Earth Day. There were many competing events that day, so we appreciate that you took the time to find our new location and purchase our seedlings.
After the sale, we moved the unsold plants back to our greenhouse. By the following Tuesday, we noticed issues with some of the remaining plants. Some had leaves that were flattened, thin or fan shaped; some had curled buds. Immediately we went into diagnostic mode, concerned about the plants we had sold. We sent samples to the University of California at Davis for laboratory analysis.
Our propagation processes were examined and reviewed thoroughly. Was it the seeds, the greenhouse environment, the potting soil, the propagators or other greenhouse visitors who caused these symptoms?
We used seeds from reputable commercial sources, new clean pots and sterilized organic seed-starting mixes and soils. The Master Gardeners who did the propagation and transplanting were trained and experienced. We carefully monitored the seedlings' growth and provided them with the right environment for a strong and healthy start.
The symptoms fit two possible causes. The worst-case scenario was a virus, but herbicide contamination of the potting soil was another possibility. Given the symptoms, tomato mosaic virus and cucumber mosaic virus were the two most likely culprits. But the laboratory results for those viruses turned up negative, so our customers don't need to worry about viruses spreading in the soil. The problem is not viral.
Still, we needed to know what did happen and what we could do to prevent a recurrence next year.
After reviewing our protocols and the growing environment, we suspect that a low-level herbicide such as Clopyralid was present in the transplanting soil. Herbicides used to control weeds in pasture can persist in animal manure, which is then used in commercial soil products. In some cases, the herbicide is present at a level too low to detect, so it may even occur in soil mixes labeled as organic.
Tomatoes are extremely sensitive; minute amounts of these herbicides can affect them.The University of California at Davis laboratory staff and university vegetable experts concurred with our suspicion that low-level herbicide residue in the soil mix was the likely cause of the damage we were seeing.
Many of the stressed plants, transplanted into healthy soil and given adequate water and fertilizer, are faring well. The damage is not transmissible. Even so, we are reviewing and revising all of our protocols from seed starting to sale day.
We had some unusual spring weather that may have impacted our seedlings. Early warm days were followed by nights with very low temperatures. Even in a greenhouse, these temperature swings can stress young seedlings. Tomatoes are sensitive to temperatures below 57°F and require moderately warm to hot weather to produce a crop. Our typical spring was not typical this year.
The Master Gardeners apologize for any problems you have experienced with tomatoes you purchased from us. We are trained to diagnose your gardening dilemmas, but sometimes we have to diagnose our own. Fortunately, our Master Gardener training teaches us where to find reliable, research-based information.
We hope to turn this tomato experience into a “citizen science” initiative. If you purchased tomatoes at our plant sale, please let us know how your plants are doing. We welcome good news and bad. How many of each variety did you purchase? How many are thriving, and how many are struggling or have died? Are your tomatoes in the ground, in a raised bed or in a pot? Did you harden them off before planting, and if so, how? What is your watering and fertilizing routine?
Remember to water your young plants daily until they are established. Give them extra water during very hot weather. Consider applying a 12-12-12 fertilizer before they bloom to give them an extra boost. An additional application of a nitrogen-only fertilizer during bloom will prolong fruit production.
The University of California Master Gardeners of Napa County appreciate your ongoing support for our mission to provide research-based information that helps you succeed in your garden.
Workshop: Napa County Master Gardeners will hold a workshop on “What's Bugging You?” on Saturday, June 18, from 9:30 a.m. to 11:30 a.m., at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Understanding pests and blights that affect your vegetables is key to managing them. Squash that doesn't grow, tomatoes with peculiar markings, artichokes full of earwigs, plants that fail to thrive − all these and more will be discussed. Bring your own problems to show and tell and learn how Integrated Pest Management techniques can help. Walk-in registration (cash or check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.