Tomato variety selection makes a huge difference.
You may have had your own tears, and understandably so. Late Blight of potatoes and tomatoes was the disease responsible for the Irish potato famine in the mid-nineteenth century. Spores are spread by rain/watering splash, insects, and wind, and through our hands and tools and through these mediums they can travel distances. 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 soil, on debris and weeds.
Fusarium Wilt is commonly found throughout the United States, is a soil and wind-borne pathogen. Plants susceptible to Fusarium Wilt are cucumber, potato, tomato, eggplant, pepper and beans. Fusarium wilt causes foliage to yellow, brown spots on leaves, leaves to curve the length of the leaf, wilt, then turn brown and die. Your plants become stunted because they can no longer function properly. Even with resistant varieties, production can be drastically reduced.
Verticillium Wilt is also a soil and wind-borne pathogen. The list of plants susceptible to Verticillium Wilt is impressive. You might have thought it was just tomatoes, but look: Peanut, Horseradish, Rutabaga, Cabbage, Brussels sprouts, Pepper, Safflower, Hemp, Watermelon, citron Cantaloupe, honey dew, Pumpkin, Cotton, Okra, Mint, Radish, Rhubarb, Castor bean, Eggplant, Potato, Spinach, New Zealand spinach, Salsify, Yard-long bean, Cowpea! Cucumber, tomatoes and strawberries are particularly susceptible.
Verticillium wilt is most active in humid climates. Cool nights and moist conditions, the kind that favors peas, tend to encourage it. It is windborne and lives in the soil, entering plants through the roots and is drawn up to stems, leaves and fruit through water uptake. At the same time, it is robbing the plant of moisture. The first symptoms of Verticillium are usually seen in wilting, yellowing and curling leaves. Discolored streaks are often seen in strawberry stems and runners, and in berry canes. Get resistant strawberry varieties like Seascape.
To determine if a plant is infected with bacterial wilt, press together two freshly cut sections of a stem and slowly pull them apart. If a “stringy” sap (bacterial growth and associated resins) extends between the cut ends, the plant has bacterial wilt.
Especially Tomatoes! And of those, Heirlooms are particularly susceptible to the wilts. Instead, get varieties that have VFN or VF on the tag at the nursery. The V is for Verticillium, the F Fusarium wilt, N nematodes. Ace, Early Girl, Champion, Celebrity, are some that are wilt resistant/tolerant. In these drought conditions, consider getting only indeterminates. In the Mother Earth News tomato survey, they found gardeners chose heirlooms over hybrids if their soil is wilt/blight free. Otherwise, the longer the gardener has gardened, the more they choose wilt resistant hybrid toms if their soil has the fungi.
Western striped cucumber beetles (on right in image) are deadly to cucumbers. They are referred to as ‘plant-wounding insects’ and also transmit bacterial wilt. Feeding on blossoms and leaves, they also spread it among squash, melons, and pumpkins which in turn spread it to nearby tomatoes. Cucumber beetles also vector viruses such as cucumber mosaic but do so much less efficiently than aphids. Spiders are one of the predators that eat the beetles. Let those spiders live! A tachinid fly and a braconid parasitoid wasp parasitize them. Grow plenty of flowers for these beneficial insects!
Radish have become my new religion! Radish repel the beetles! Best to plant your radish before installing your transplants or have it up before the seedlings start growing from seed. Grow your radish companion along where you will let the vine travel, among squash and pumpkins, cucumbers and TOMATOES! The part of the vine growing up over an arch or up a trellis won’t be helped, so if you have space and uninfected soil, you may opt to keep your vines on the ground. If you do have infected soil, but choose to keep your vine on the ground, keep that area weeded and don’t lay on mulch. Weeds and mulch keep soil moist. The fungi dry and die on hot dry soil. Water only where you staked, at the planting basin. Plant enough radish so you can eat some, but as a beetle repellent, let it grow out so the whole plant is big and protecting your cukes, tomatoes and other vines.
The Mulch exception is straw.
- Broccoli also repel cucumber beetles. Grow cucumbers on the sunny side under over summering Broccoli. Put in plenty of straw mulch, 3-6″ deep, to keep the brocs, primarily a winter plant, cool and the cukes off the ground. Whenever you see these beetles don’t fall for how cute they are. Anticipate how they drop to the ground when you reach for them, so approach from below, hand open. Catch & Squish.
- Under tomatoes and cucumbers not with Broccoli, apply straw mulch only an inch thick! No more than that. You want light and air circulation, for the soil to warm and dry some. Washington State Extension says: Straw mulch can help reduce cucumber beetle problems in at least 3 different ways.
- First, mulch might directly slow beetle movement from one plant to another.
- Second, the mulch provides refuge for wolf spiders and other predators from hot and dry conditions, helping predator conservation.
- Third, the straw mulch is food for springtails and other insects that eat decaying plant material; these decomposers are important non-pest prey for spiders, helping to further build spider numbers.
- It is important that straw mulch does not contain weed seeds and to make certain that it does not contain herbicide residues which can take years to fully break down.
Transplant rather than direct seed! Tiny seedlings are most susceptible to cucumber beetle feeding damage and to bacterial wilts.
Special Planting and Growing Tips!
At the community gardens I have seen gardeners give up growing Toms and Cukes due to the wilts. But if you are willing, you can do it! Here’s how!
Plant later, like May or June, for warmer dryer soil.
Select the right varieties! Give your plants the best chance possible. Remember, if one plant gets the wilts, so will your others. The most important choice you will make is selecting disease and pest resistant varieties! Since pests like aphids and cucumber beetles carry diseases like the wilts, selecting varieties resistant to those diseases is essential. Cornell University has Disease Resistant Vegetable Varieties Lists! The lists are alphabetical. Not all varieties are listed, but this will give you a great start. Check on local university recommendations, cooperative extension, what Master Gardeners in your locality have to say. See what the nurseries near you carry or what the farmers market farmers are growing successfully. When researching, always look at the post date or update date to get current information.
And… Cucumber Beetles have their preferences! Bitter is their favorite. Not interested in watermelon at all, but watermelon does get the wilts, just from other sources! Varieties make a huge difference. Long story short, less C Beetles, less Wilts = healthier Tomatoes!
The strongest cucumbers I have grown are the Natsu Fushinari longs. They produced like crazy, and the plant was healthy and lasted longer than any I have ever grown.
Regarding soil fungi like Fusarium and Verticillium wilts/fungi, how you plant and care for cukes and toms is super important! Cucumbers are even more susceptible than tomatoes to the wilts fungi, die pretty instantly, in about 3 days when they get infected. So when you plant them, treat them similarly to your tomatoes if you have wilts fungi in your garden.
- Plant cukes and toms on a raised mound/basin with the bottom of the basin above the regular soil level. This allows good drainage. Make the basin low area as big as your tom’s feeder roots will grow to. Once planted, top the bottom of the basin with a 1/2″ of compost, cover that with only 1″ of straw to let in air flow and sun to dry the soil. If you are planting early in cool moist soil, do not add the compost and straw layers………
- Keep ALL the LEAVES OFF THE GROUND from the get go. Leaves touching the soil is the main way toms get the wilts. Remove lower leaves that might touch soil when weighted with dew or water from watering. Keep a regular watch for new foliage sprouting at ground level and remove it on sight! AVOID WATER SPLASH when watering at ground level. The fuzzy damp leaves of toms and eggplant are perfect fungi habitat.
- When your toms 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. Since toms have deep roots, they will get plenty of water from what you give neighboring plants. Water near them but not at them or on them. In fact there are farmers who dry farm tomatoes! Read more!
- If you are commingling beans with cukes lower along a trellis, plant the beans between the raised cucumber mounds. Beans don’t get the wilts, but love the water, so lower is good. They are a big plant with continuous high production and short roots that need to be kept moist. Mulch ASAP with straw. Keep lower possible ground touching leaves trimmed away. Later the straw mulch will keep fruits off the ground out of the insect zone. Put a tall enough stake in the middle of each basin so you know where to water when the leaves get big and cover the area. Water gently BELOW the leaves at ground level, no splash. Keep those leaves dry. Keep removing lower leaves as your plant grows.
. - Generously plant radishes before seeding your cukes, or immediately at transplanting to repel the cucumber beetles. You can remove some radishes as they get bigger and you have enough to help the other plants. You must let them grow out to protect plants’ blossoms higher on the trellis. When they get tall you may have to tie them to keep them up in the area they are needed.
. - Biodiversity is another form of companion planting. Hot peppers emit a chemical from the plant roots that helps prevent Fusarium wilt, root rot, and a wide range of other plant diseases! Eggplant releases potassium that tomatoes benefit from. A wise choice may be to alternate, zig zag, okra, peppers, eggplant and tomatoes, putting the shorter plants slightly on the sunny side. If you are growing shorter varieties of okra, maybe your tomatoes will be the tallest. You could plant a tomato, a pepper, okra, then an eggplant and pepper, okra, tomato, pepper. You get the idea, mix it up! If you are doing side by side rows, plant each row in a different order. This stops pests and diseases from going plant to plant along a row, or row to row. You are using the stars of your garden as companions!
. - Since the fungi are airborne as well as soil borne, plant in different places as far apart as possible. Plant so leaves of one plant are not touching another plant. Remove sickened foliage ASAP to reduce fungi population and slow spreading. When possible, 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. Wash your hands often, dip your tools in alcohol. Trimming away infected leaves is a sad and tedious process. It’s practically impossible not to spread the fungi as you touch leaves that have it and try to remove them without touching any other stems or leaves. The very cuts you make are open to fungi. Then, naked stems are susceptible to sunscald – see image above. You come back a few days later and more leaves are wilting. The disease is internal, has spread out to the leaves. At some point soon after that, a lot of gardeners pull the suffering plant. It’s done. Not good to leave it and let windborne fungi infect neighboring plants. Do not compost infected plants or trimmings. The fungi has amazing survival ability and being soil borne, it is right at home in your compost. Put it in the trash, carefully bagged so as not to spread or leave any trace. Wash your hands, dip your tools in alcohol. If you can, burn the infected plants on a non windy day.
- The wilts can’t be stopped. Sooner or later the plant leaves curl lengthwise, get the dark spots, turn brown then blacken, dry and hang sadly. Plants can produce but the fruit doesn’t ripen properly if it does produce. It’s agonizing to watch. Sometimes they somewhat recover later in the season after looking totally dead. You had stopped watering them, summer heat dries the soil and kills enough of the fungi for the plant to be able to try again. But production is so little and fruits don’t ripen properly. It’s better to pull it, reduce the fungi population that can blow to other plants. The safest bet is to remove the entire plant. Get all of the root as best you can. The root is where the wilt’s mycelium first congregate and infected roots left in the ground will start the whole process again. Replant in a different place if possible….can’t be stopped.
That said, consider this! 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 1/4 cup of BLEACH to a gallon of water [add a 1/4 to 1/2 teaspoon dish soap as a surfactant so it will ‘stick,’ and do it as early as possible in the day] 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.
The summer of 2019 I finally got up the courage to try Leroy’s Bleach mix! IT WORKED! I started after my plants were showing wilts signs, figured I had nothing to lose ~ totally scared it would kill my tom, I tried it on one, frightened to come the next day to see how it was. Just like Leroy says, it did not kill the plant! Whew! I wasn’t religious with the weekly treatment but my plants vastly improved, there was plentiful production that other gardeners commented on, and production lasted months longer than usual!.
Preventive Foliar Mix that can help!
Apply to newly installed transplants, and during the season every 2 to 3 weeks, so new growth will be covered. Wet both the undersides and tops of 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
After the tomatoes set, add some Nitrogen. Stressed plants are the most susceptible to the fungus. Boost your plant’s immune system with some worm castings at the same time. You don’t want to add too much nitrogen to your tomatoes before they set fruit because it leads to more leaves, less fruit. Add N only once. Water regularly and deeply. Use well-balanced, slow-release organic fertilizers that aren’t overly heavy with nitrogen. Alfalfa pellets will do the job. A healthy plant tends to fight off the spores.
Blight can also be transmitted through seed, so NO seed saving from infected plant fruits. Fresh seeds from a safe source and resistant varieties are in order.
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 dear plants may not win the battle.
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, creates gaps between the tomato plants. Remove suckers. See the spruce! Thin growth inside the cage if the leaves get too dense. You want 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.
At the end of the season remove all infected debris, don’t compost or put in green waste containers. Bag it and trash it. Don’t leave dead tomato, eggplant or peppers in the garden to spend the winter – especially if you are in a community garden. Pull weeds because spores can over-winter on weed hosts. Many weeds, including dandelions and lambsquarters, are known to host Verticillium wilt. During our winter season, turn your soil about 10 inches deep. Let the soil dry and the fungi die. Burying the spores helps remove them, it disturbs cucumber beetle eggs and exposes snail eggs to die!
If you have space, crop rotation is an important tool in fighting wilt. If you’ve had trouble with wilt, don’t plant potatoes, eggplant, or other Solanaceous vegetables where any of them have grown for at least four years.
Practice prevention, be vigilant. If you don’t have wilts in your soil you are so blessed!
Updated 1.26.23
Love your Mother! Plant bird & bee food! Think grey water! Grow organic! Bless you for being such a wonderful Earth Steward!
The Green Bean Connection newsletter started as correspondence for the Santa Barbara CA USA, Pilgrim Terrace Community Garden. Both of Santa Barbara City’s remaining community gardens are very coastal. During late spring/summer we are in a fog belt/marine layer area most years, locally referred to as the May grays, June glooms and August fogusts. Keep that in mind compared to the microclimate niche where your veggie garden is.
Leave a comment