Tomato, Part II (Questions 42 - )
42. Q. I planted the tomato varieties which you recommended and they are loaded with tomatoes. Now the leaves are beginning to turn yellow, then brown, then die from the bottom of the plant. What should I do; will this kill my plants?
A. You and everybody growing tomatoes are having the same problem. Tomato plants are developing brown spots on the lower foliage. This is the result of a fungus infecting the foliage causing a disease known as early blight. Early blight is an annual problem for most gardeners. It normally develops into a problem when plants have a heavy fruit set and the area has received rainfall. Spores from the fungus are spread to the lower foliage by wind and splashing rain. Leaves must be wet for infection to occur. At 50 degrees F. the leaves must be wet for 12 hours for infection, but at temperatures above 59 degrees F., the length of time for infection is only 3 hours. Leaf spot development is most severe during periods of cloudy days and high humidity. To control the fungus, foliage applications of a fungicide must be made every 7 days until moist conditions (dew included!) no longer exist. Applications should begin when the first fruit is slightly larger than a quarter. Chlorothalonil (Ortho Multipurpose Fungicide or Fertilome Broad Spectrum Fungicide) and mancozeb hydroxide (Kocide 101) are fungicides used on tomatoes for early blight. The copper fungicides also are affective against the foliage and fruit-infecting bacterial pathogens. Benlate (Greenlight Systemic Fungicide) should also be added every second spray application to prevent Septoria leaf spot. All listed fungicides can be mixed with insecticides or other fungicides except the copper-based materials (Kocide). The copper fungicides have a high pH which will reduce the life of many insecticides and some fungicides. Kocide is the only effective organic control for this pestilence.
43. Q. What is the best-tasting tomato to plant in the spring garden? I recently read an advertisement for an easy-to-grow tomato plant which requires no staking, no caging, no pruning and no trimming yet produces huge luscious, mouth-watering tomatoes all season long. Have you tested this variety?
A. I saw the same advertisement. I couldn't afford to test this variety, whatever the true name might be, since one plant costs $3.50. Extension horticulturists use a minimum of 24 plants per testing location and have locations throughout the state so you can be assured that Extension-recommended varieties are productive, provided they are grown properly. About taste, anyone who recommends a certain variety to another person because of taste is being fool-hearty. Everyone has a different taste preference. This was proven this fall when I conducted a taste test of the leading varieties in this area. All varieties were grown in the same field, harvested at the same maturity, and sliced so that appearance would not be a factor. Several hundred participants indicated strong preferences for each of the different varieties. For instance, the person who loved the Bingo tomato variety may have disliked the Whirlaway tomato variety and vice versa. Interestingly enough, some married couples had different preferences so unless both Bingo and Whirlaway varieties were planted and tomatoes separated, one of the spouses strongly disliked the tomatoes which were planted. The tomato rage of '92 named Surefire had what is best described as a non-controversial flavor -- people neither loved it or hated it. Surefire was judged to be the meatiest entry and all agreed it would be the best for sausas, sauses and long-storage. With all of that verbiage and data to consider, I will make this recommendation. Transplant several plants of Extension- recommended varieties such as Bingo, Whirlaway, Heatwave, Celebrity and Carnival and judge their flavor for yourself in your gardening conditions. The Surefire tomato variety should be planted to produce the earliest fruit of the year and a meaty tomato which can be used in sausas as well as for fresh consumption. Spring-planted Surefire is a bonus-supplement to the standard Extension-recommended varieties.
44. Q: How do you keep squirrels from eating tomatoes?
A: Trap and release (into the skillet) or kill. Or cover base of plants up about 3-4 feet with Grow-Web or surrounding bearing tomatoes with a wire barrier such as hardware cloth or small mesh chicken wire. Lead poisoning or number 8 shot (propelled out the barrel of a shotgun) works too but might damage the plants or fruit.
45. Q: We planted tomato transplants earlier this year which are now over 6ft tall. The problem is that considering how many plants we have the fruit set ratio is pretty poor. The plants are near a tree but because of the direction of the sun get quite a bit of sunlight. Maybe too much. When the temperature went over 100 degrees, we constructed a nursery shade cloth which allows 50% of the sun to come through. We also mulched the tomatoes with sawdust. The soil is compacted and when we watered it the water would sit on top, taking forever to absorb into the soil. To remedy this, we added redwood compost and organic compost. This helped loosen up the soil. Could we be having soil problems still? Our winter crop of onions and garlic was very poor - extremely slow to bulb and the bulbs were very small. We had planted Beefsteak, Early Girl and Roma.
A: You have too much shade!! Tomatoes and fruiting plants MUST HAVE 8-10 hours of direct DAILY or fruit production WILL BE DIMINISHED or ELIMINATED. The tomato varieties you planted are indeterminate and especially sensitive (have few blooms and grow tall and lanky) to insufficient sun locations.
Sawdust is the worse mulch you can use!! When incorporated into the soil before complete decomposition has occurred, it robs the plants of nitrogen and causes stunted growth and small bulbs as you saw with the onions.
Remove as much of the undecomposed sawdust as possible -- from now on use shredded leaves or grass clippings. Double your rate of fertilizer from 2 pounds of a complete, slow-release formulation such as 19-5-9 to 4-6 pounds per 100 square feet. Plant tomatoes, peppers, eggplant, etc. in the sunniest location available. Try to find determinate or semi-determinate varieties such as HeatWave, Celebrity, Merced. Plant broccoli, lettuce, celery, cauliflower, green onions, etc. in shaded areas.
46. Q: My tomatoes, potatoes, peppers, eggplant and marigolds have all been in the garden awhile--(2 weeks for most and a month for the spuds. This week they all developed yellow leaves in their growth centers. Otherwise, plants look healthy and big. What gives? The yellow is solid-- not veined like iron deficiency. Plants are all mulched heavily with shredded oak leaves.
A: With the on and off cold temperatures we have been experiencing, I'll bet those tomatoes, peppers and eggplant are growing slowly. That could cause the yellowing centers combined with nitrogen deficiency or severe iron deficiency. When huge quantities of organic material are added to a planting area before the organic material decomposes, micro-organisms require nitrogen to accomplish the decomposition. In a marginally fertilized planting area, this nitrogen drain by micro-organisms can cause plant deficiencies. You should have added at least 3 pounds of a slow-release fertilizer such as 19-5-9 before planting and should sidedress (two tablespoons of ammonium sulfate 21-0-0) sprinkled around each plant and watered in) every two weeks after plants have marble-size fruit. If you under-fertilized because of the excess organic material, make a sidedress application of nitrogen now. In cause this is a severe iron deficiency, let's use a liquid iron product and water around each plant with the appropiate mixture. The response may be slow in this cold weather since plants may be a bit stunted. You might consider replacing what plants you can since a stunted plant is a slow grower and produces less in the long run. Virus infection can cause the same yellowing appearance but I think it is too soon for young transplants to be infected with virus.
47. Q: My tomatoes seem to be growing very well, lots of fruit, etc. However, every year, the leaves begin to curl upwards (from the edges) and the veins look dark blue or purple. any ideas as to what could be causing this? The fruit, once this begins to happen, does not ripen properly - it has a whitish color to it and stays hard; although many times a portion of one tomato will be ripe and still have the affected part on it.
A: You have done a superb job describing the exact symptoms of Tomato Spotted Wilt Virus (TSWV). Destroy those plants which begin to show the symptoms. In most years, only 15-20 percent of the plants show the symptoms -- some years it damages more.
48. Q: I was wondering why tomato plants close together do so much better then those I plant further apart, does this have something to do with a cooperative growth hormone diffusion process?
A: Tomato plants planted close together or in high density produce more fruit per area but the fruit is smaller. Also, if you plant transplants closely and some die from Tomato Spotted Wilt Virus (TSWV), others will "fill in" for the dead ones and sometimes make it seem that the virus was not present. So if you plant for yield, plant close; if you plant for size, give them space.
49. Q: I've read the descriptions of tomato pinworms and fruitworms, but these descriptions do not seem to fit the holes in my ripe tomatoes. Only ripe tomatoes have a single, pea-sized hole, about one inch from the stem which seems to have no living creature associated with it. If left for a short time the tomato rots rapidly after first turning pale on the stem end surface. My neighbor's tomatoes have the same problem- he's never seen such holes in 35 years of growing tomatoes! What have we got?.
A: The damage you describe is from a tomato fruit worm (same thing as tobacco bud worm, corn earworm and cotton boll worm). They can be very damaging in the late summer and not easily controlled since the Bt. products such as Dipel and Thuricide are not as effective because the worm feed directly on the fruit. I would still recommend using Bt. and mixing a teaspoon of liquid detergent per gallon of spray and direct it at the fruit. Spray every 5 days for 5 consecutive days since the Bt biodegrades during periods of high temperature and sun exposure. Apply sprays late in the evening. If you had not described the hole or damaged area of fruit as large as a pea (pea-sized hole) I would have said it is pinworm but its hole is the size of a 20 penny nail. Sometimes the tomato fruit worm is there and sometimes not. The Bt applications may help but this is a serious problem for fall tomatoes.
50. Q: I got lots of nice tomatoes this year but they all have small hard yellow spots on them. Can you please tell me what causes this and if there is a preventative for the fall crop?
A: We are having late summer weather (heat) in spring this year so the things which cause the hard, yellow spots such as plant stress, sunscald and insect damage are present. I am afraid you may have the same problems this fall. You might try another tomato variety which has more foliage which can provide protection. TIMES ARE HARD EVERYWHERE!! Just cut the yellow, hard spot off and enjoy the rest of that delicious, fresh tomato.
51. My friend is growing three varieties of disease resistant cherry tomatoes of which his favorite is Gardener's Delight, grown from English seed. He has produced these for several years with no problems but has had problems with green shoulders for the past two seasons. Both years there was a cool spring with a sudden burst of heat. He wonders if the cold weather followed by a blast of hot weather had an impact on the plants' ability to absorb potash and, therefore, the green shoulders are caused by a potash shortage?
Other varieties he is growing are Big Beef, Fantastic, Super Fantastic, Siletz and Husky Red. I gather the problem of green shoulders is fairly universal among all varieties.
A: Greenshoulders is more of a varietial problem than an environmental one. The potash theory sounds good but doesn't pan out in the real world -- in Texas we select against this trait in varieties and rarely ever see it anymore. Check with the Extension Service in your area and see if they have a list of recommended varieties. I haven't grown Fantastic or Super Fantastic for years but I don't remember green shoulders being a big problem with these varieties. Environmental conditions can accentuate the problem but not cause it all-together.
52. Q: Is blight transmitable by using the same cages as last year? I moved where my tomatos were planted from last year and they still developed blight. I did notice though that it only seemed to happen to those plants in old cages. I had to buy a few new cages and none of those plants developed what I think is blight. Would cleaning the cages with 10% chlorine mix when stored this winter help?
A: Virus is transmitted by an insect vector which must feed on a living plant which is contaminated then feed on a healthy victim. Diseased plant material should be removed and destroyed but wire cages have not been known to be a source of contamination. Virus symptoms are so random they are a mystery to those of us who see them every day. Keep the faith!! and don't worry about chloroxing the cages.
53. Q: We have had problems starting tomato plants (primarily) and other vegetables from seeds. We try and start the seedlings indoors a couple of months before planting them outside. What do we need to do to make our seeds grow?
A: Starting seed at home can sometimes be a frustrating and disappointing project. That is why most of the varieties I recommend are available in a quality transplant form from local nurseries. Many times the seed of good tomato varieties is very expensive and not available. Those varieties for which seed is available are sometimes open-pollinated types and the seed is old and difficult to germinate. The mistake most homeowners make is keeping the potting mix too wet and planting the seed too deep (it should practically be on top of a moist seedling mix covered NO MORE than 1/4 inch with a light seedling mix). Humidity should be kept high by covering the seedling tray with plastic and keeping it out of direct sun so as not to "cook" the young, tender seedlings. Once (immediately!) seedling emerge, they must be exposed to a full sun condition ALL DAY LONG. Doing everything right will not germinate seed which is old and dead, regardless of the number of old, dead seed you use!
Tomatoes and Spider Mites
54. Q: I have a raised bed garden and have battled spider mites to no avail. They have ruined my tomatoes. I use cypress mulch in my garden as well as a weed block. Do I need to get rid of these things to start the garden this year, spray my soil with Kelthane or something else? Please help I want my garden back.
A: Spider mites do over winter in mulches and plant debris left over from the previous summer. ╩But if you think that you will avoid mites by burning, scorching, "poisoning", or otherwise sterilizing your garden soil, you are mistaken. ╩Spider mites have an admirable capacity to find tomatoes even if the tomatoes are planted on virgin soil. ╩They apparently do this via wind transport, or some other means we haven't quite figured out.
Unfortunately, there are not many magic bullets on the market for spider mite control on vegetables. ╩I recommend an integrated approach:
- Do not compost mite infested plant material (There's no use giving mites a head start. ╩Unless your compost pile is uniformly hot enough to kill mites, I'm convinced this is another way mites can infest a garden.)
- Inspect your tomato seedlings for mites and choose only mite free plants (Again, let's not help the mites by giving them an early start). ╩With a hand lens, check the undersides of a few leaves of every plant you purchase.
- At the first sign of infestation (assuming you do check your plants a couple of times a week for the first signs of spider mites on leaf undersides), do one of the following: try blasting mites off with a stiff stream of water directed at leaf undersides (this can significantly delay mite population buildups, if done thoroughly); apply horticultural oil or insecticide soap sprays; pick off and destroy any leaflets you find mites on.
- Apply Kelthane, if you have it. ╩Kelthane is the last good miticide labeled for use on vegetables. ╩It is difficult to find in stores any more, but old stocks can still be used for this purpose.
- Get your spring tomatoes started early, and remove plants when they become mite infested. ╩Instead of battling the mites, give in and focus on a late summer planting of tomatoes. ╩Sometimes the fall tomato crop is easier to grow without spider mites. ╩Check with your local county recommendations for the best time to start a fall tomato garden. Michael Merchant, PhD, BCE; Urban Entomologist; Texas Cooperative Extension
| Vegetable Page | PLANTanswers Home | Aggie Horticulture || Vegetable Page | PLANTanswers Home | Aggie Horticulture |