What’s happening with my tomatoes?!
This?! Or this?
This is bar none, the most common summer question I get asked! Potatoes, tomatoes, and the various forms of lettuce are the top three favorite vegetables in the US, so you can see why this is THE question! Since fungi spread as simply as by the wind, I will be campaigning for more tomato plant care, starting with what people can do now to keep the fungi from overwintering, then in the spring to lessen its chances. There are more things that can be done than I knew! Read on! About Fungi To emphasize the potency of these fungi: Late Blight of potatoes and tomatoes, the disease that was responsible for the Irish potato famine in the mid-nineteenth century, is caused by the fungus-like oomycete pathogen Phytophthora infestans. It can infect and destroy the leaves, stems, fruits, and tubers of potato and tomato plants. Before the disease appeared in Ireland it caused a devastating epidemic in the early 1840s in the northeastern United States. Not only do the fungi feed on your tomato plants, but take a look at your potatoes, peppers, eggplant, cucumbers and beans! See those yellowing leaves? Remove and dispose of them ASAP! That removes zillions of spores so they can’t spread. The wilts and blights also affect trees! Sadly, not only do your plants look depressing, production is zilch, they die an unnatural death. Remove, replace. Be happy. How do fungi work? Spores are spread by rain/watering splash, insects, and wind, and through our hands and tools (wash your hands and tools after handling infected plants) and through these mediums, can travel distances. That’s why it is so important, in our community garden, to tend our plants, so our neighbors’ plants won’t also be infected. Educate your plot neighbors, better yet, send this to them! Spore spread is most rapid during conditions of high moisture, marine layer days, and moderate temperatures (60°-80°F). Once established, the fungi can over winter in your garden on debris and weeds. What they look like on your plant:
14 Fungi Preventions!
Cultural control practices alone won’t prevent disease during seasons with wet, cool weather. However, the following measures will improve your chances of raising a successful crop.
- Buy toms that are tagged VFN, or just VF – that’s Verticillium Wilt and Fusarium resistant or tolerant. Varieties that set fruit early, at lower temps, are Early Girl Improved, Fourth of July, Enchantment. Excellent resistant varieties are Champion, Husky Red, Better Boy, Ace Hybrid, Celebrity.
- Plant only healthy-appearing tomato transplants. Check to make sure plants are free of dark lesions on leaves or stems. If starting transplants from seed, air-dry freshly harvested seed at least 3 days.
- Remove volunteer tomatoes and potatoes. If they are a not a resistant or tolerant variety, when they get sick, they increase the chances of your resistant varieties having to fight harder to live, and your good plants may not win the battle. Do not let volunteers grow, even on compost piles, cute as they are. Infected tomato refuse should be put in the trash.
- **Create a soil barrier, mulch! You can layer newspaper/cardboard covered with mulch or grass clippings. Anything organic, as you wish. One to 2 inches of straw is easy to lay on. You want to create a splash barrier. Seal the soil and you reduce the chances of spores finding your plant. Bottom line, you don’t want your soil to contact your plant.
- **Avoid wetting foliage when watering, especially in late afternoon and evening. Water at the ground! Watering the leaves creates a humid micro climate; the fungus produces spores. Dry leaves. Dry leaves. Dry leaves. No moisture, no spores.
- **Air circulation, plant staking and no touching. Air circulation allows the wind to blow through your plants. This allows the timely drying of leaves and it helps break up micro climates. If your plants are packed too tightly together, they themselves become barriers to drying. Staking your plants to poles and using cages helps them grow upright and it creates gaps between the tomato plants. You want to wind and sun to reach through and around your plants. Moisture is needed for fungi to spread. Dry is good. Tomatoes should be planted with enough distance that only minor pruning is needed to keep them from touching each other.
- **Spray proactively. Wettable sulfur works. It is acceptable as an organic pesticide/fungicide, is a broad spectrum poison, follow the precautions. It creates an environment on the leaves the spores don’t like. The key to spraying with wettable sulfur is to do it weekly BEFORE signs of the disease shows. Other products also help stop the spread. Whatever you select, the key is to spray early and regularly.
- **When they are about a foot tall, water neighboring plants, but not your toms. That keeps the soil drier near your plant, so the fungi can’t thrive there. Your tomatoes will get plenty of water from their deeper roots.
- **Remove bottom leaves, again, no touching (the ground), and prune your plants. Barbara Pleasant at Mother Earth News says, ‘When the lowest leaves are removed just as the first leaf spots appear, you also remove millions (zillions) of spores. And, because the bases of pruned plants dry quickly, the spread of the disease is slowed because early blight fungi need damp leaves in order to germinate and grow.’ Create an 18 to 24 inch barrier gap or safe space between your garden soil or mulch and the first leaves of the tomato plant. If the spores can’t splash upwards and reach the leaves, they can’t take hold. The stem usually isn’t a place for the spores, though it can be. Best is to remove the bottom leaves before the spores start! If you have large plants, you might consider cutting off some branches to let the sun and wind blow through the main body of your tomato plant. But, some gardeners don’t recommend pruning or snipping the suckers, the mini branches formed between the trunk and branches, because spores can enter through these cuts. If you decide to prune, the less cuts the better. Prune on hot, dry, unwindy days, mid morning to midday, after dew has dried, so cuts can dry and heal with less chance of airborne fungi getting into them. Try not to touch the cuts after they have been made. Use clippers for a clean cut.
- **Remove infected leaves immediately. A leaf should be completely green. Look for brown spots or yellow spots or distress. Remove leaves and prune when it is dry and sunny, not windy. Wash your tools and hands often.
- After the tomatoes set, add some nitrogen. A healthy plant tends to fight off the spores. You don’t want to add too much nitrogen to your tomatoes before they set fruit. Too much nitrogen before fruiting leads to more leaves and less fruit. Add N only once.
- **Rotate your crop if possible. Because fungi also affect other plants, rotation in small gardens isn’t practical or even possible. But if you have the room, move your tomatoes to areas that are fungi free.
- ****At the end of the season remove, don’t compost, all infected debris and surrounding debris. Pull all the weeds because spores can over winter on weed hosts. You want to reduce the number of spores laying in wait.
- **The spores aren’t super spores. During our winter season, turn your soil about 10 inches, burying the spores helps remove them, and it also exposes snail eggs to die.
Preventive Foliar Mix that does wonders!
Apply every 2 to 3 weeks, so new growth will be covered. Wet under and over the leaves. Per gallon add:
- One dissolved regular strength aspirin
- 1/4 Cup nonfat powdered milk
- Heaping tablespoon baking soda
- 1/2 Teaspoon mild liquid dish soap
Water your plants with an aspirin?! Salicylic acid, in aspirin, triggers a defense response in tomatoes and other plants as well! Adapted from eHow: The main benefit of aspirin in planting involves aspirin’s ability to fend off potential plant diseases.
- Purchase regular strength aspirin. The brand does not matter; purchase the cheapest brand that is available.
- Mix together one aspirin with one gallon of water. Combine the ingredients well, so that the aspirin is distributed evenly throughout the liquid.
- Add a dash of mild liquid soap to the mixture. This is used as a way to help the aspirin water stick better to the tomato plants. Once the soap is added, attach a spray nozzle to the gallon jug and it is ready to use.
- Spray the tomatoes when you first set them in the ground. Aspirin sprayed directly on seeds improves germination, on plants it stimulates the growing process. There is no need to soak the area. A light and gentle spray will suffice.
- Continue to spray the aspirin mixture on the tomato plants every 2 to 3 weeks. You are going to notice that the plants stay healthier and attract fewer insects.
Per a comment by Leroy Cheuvront at Heavy Petal blog: I have had the blight and have stopped it from destroying my tomato plants. All you have to do is mix 2 ounces of bleach to a gallon of water and drown the plant from top to bottom, it will not kill the plant. I do it every seven days and the blight has not returned. — June 18, 2010. It sounds scary, but I bet it works! I would test this principle on ONE plant to be sure it is safe to use. Solarization In the past ten years, some enterprising Israelis came up with solarizing. Moist soil is covered with transparent plastic film for four to six/eight weeks in the summer. It takes that long to heat the soil to a temperature and depth that will kill harmful fungi, bacteria, nematodes, weeds, and certain insects in the soil. Solarization can be a useful soil disinfestation method in regions with full sun and high temperatures, but it is not effective where lower temperatures, clouds, or fog limit soil heating. Solarization stimulates the release of nutrients from organic matter present in the soil.
Solarization also kills grass by heating up the soil when daily temperatures exceed 80°F. Weed eat or mow the area as short as possible. Moisten the soil and cover the area in clear plastic for 10-14 days, until the grass is dead. Although cloudy weather will slow things down by cooling the soil under the film, a few weeks of sunshine will improve your soil dramatically, easily, and inexpensively. If you live in an area with cool or cloudy summers, or if you just don’t want to wait all season, you can speed up the process by adding a second sheet of plastic. Using the hoops commonly used to elevate row covers or bird netting, raise the second sheet of plastic over the ground-level sheet. The airspace between acts as a temperature buffer zone during cloudy weather and the combination of the two sheets of plastic serves to raise the soil temperature an additional 6 degrees. The goal is to raise and maintain temperatures in the top 6 inches of soil to a level between 110 to 125 degrees F. After several days of sunshine, soil temperatures rise to as high as 140 degrees at the surface and well over 100 degrees as far down as 18 inches. Do not mix untreated soil into the solarized bed And please, do NOT compost diseased tomatoes, or any other diseased plant. That’s how you spread soil born fungi, let alone that they are also spread by wind, are airborne. If your neighbor has a diseased plant, don’t be shy to respectfully and gently ask them to remove it. Remember, they raised that child. How hard was it for you to give up your plant? Especially the first time. See? They may not even know about wilts. Educate them if possible. Tell them how you learned about it. Offer to send them the link to this page. See also Biofumigation Biofumigation is a sustainable strategy to manage soil-borne pathogens, nematodes, insects, and weeds. Initially it was defined as the pest suppressive action of decomposing Brassica tissues, but it was later expanded to include animal and plant residues. Other Tomato Questions & Cures – Holes, spots, brown areas? Here is an IPM (Integrated Pest Management) image page from UC Davis that is likely to answer your question! It includes diseases and pests. See more images at Colorado State U Extension. Marion Owen, Fearless Weeder for PlanTea, Inc. and Co-author of Chicken Soup for the Gardener’s Soul says ‘Keep your hands in the dirt, and your dreams on a star!’ I agree! To the fattest, bestest tomatoes ever!!!! Cerena