Mark Williams, Souvestre, Robert J. | 10/1/2010 1:15:18 AM
In this article:
|FAQs Home Vegetables Table of Contents|
Answers to frequently asked questions about vegetables grown in home gardens available in three parts.
Q. What causes my radishes to fail to bulb fail to bulb?
A. Radishes will fail to bulb for several reasons. Usually, they are not properly thinned and growing too close together. Radishes should be seeded 2 to 3 seeds per inch and then thinned when they are about 1 to 2 inches tall to a spacing of at least one inch apart. Radishes will also not bulb properly when forced to mature during temperatures above 80° to 85°F. They should be grown in full sun or close to that. Improper fertility, wither, starvation or high N can also create this problem.
Q. Sometimes my radishes have a hot, bitter flavor rather than the typical radish taste. What is the problem?
A. Generally, off-flavored radishes are due to planting at the wrong time or poor cultural practices such as low fertility or low moisture resulting in slow growth. For highest quality, radishes should grow fast. Fast growth can be brought about by adequate fertility and maintaining the soil in a good moisture condition.
Q. What causes roots of radishes to crack?
A. This is usually a matter of waiting too long before harvesting the radishes. Cracking is caused by fluctuations in moisture which causes the root to rapidly swell and crack. This is especially important near maturity or expected full size of the radish roots.
Q. Are the leaves of radish plants edible?
A. Radish leaves are not poisonous and can be consumed although they have a somewhat strong, bitter flavor. There may be some dishes or some methods of preparing radish leaves which would make them more palatable, but for the most part they lack a taste or flavor desired by most.
Q. What are winter radishes and how do they differ from regular garden radishes?
A. Winter radish varieties produce very large roots which may be round or elongated and white, red or black. They require a long season for full growth. The roots may be eaten raw with vinegar or cooked like turnips. The flavor of winter radishes is usually pungent and the texture more fibrous and less crisp as compared with common garden radishes. They can be left in the cool ground much of the winter as a means of storage.
Q. My radishes have a black, crusty growth around the radish globe.
A. This is Scab and is a soil-borne disease. It can best be controlled by rotation within the garden to avoid planting in infected soil. Choose a soil low (5.5) in pH.
Q. Can rhubarb be successfully grown in Louisiana?
A. Rhubarb is a very popular garden vegetable in northern areas of the United States but unfortunately will not do well in Louisiana. Rhubarb is a cold resistant perennial that thrives best where maximum daytime temperatures average no more than 90°F. Therefore, it will not grow well in most areas of Louisiana and will produce only thin leaf stalks which are spindly and of poor color even in the most northern areas.
Q. Each year my spring planted spinach sends up a flower stalk about the time I think it is ready for harvest. What causes this and what can be done about it?
A. Spring planted spinach has a tendency to hurry into its flowering phase which stops production of edible foliage. Flowering of spinach is affected by length of day, temperature and variety. Bolt resistant varieties, often called “long standing”, should especially be used in the spring. Planting should be done as soon as possible in the early spring and should cease 6 to 8 weeks before daytime temperatures are expected to average over 75°F. Bolting is usually not a problem in fall planting which should occur about 4 to 6 weeks before the first average frost occurs in the fall.
Q. How do I keep my spinach growing vigorously rather than seeming to slow down?
A. Spinach responds to liberal applications of a nitrogen fertilizer which encourages growth and production of leaves. Applications of ammonium sulfate should be applied as a side dress to high pH soils at the rate of 2 to 3 tablespoons per 10 feet of spinach row. Applications should be made when the plants are about 2 inches tall and again after the first harvest.
Q. Should spinach be harvested by removing the outer, older leaves or by pulling up the entire plant?
A. This probably depends upon whether or not it is a spring or fall planted crop. In the spring, spinach will go to seed relatively quick so perhaps the best method harvesting is by pulling up the entire plant. When planted in early fall for winter harvesting, maximum production will be maintained by harvesting the outer leaves when they are first mature and allowing the plant to continue to grow and produce additional foliage.
Q. I’ve heard that spinach is extremely high in minerals and vitamins but also contains high levels of something which can cause problems. Is there any truth to this?
A. Spinach contains fairly high concentrations of oxalic acid which may interfere with the utilization of calcium or magnesium in the diet. The same is true for rhubarb and swiss chard. It is a fair source of protein, CA, F, Fe, K, vitamins A and B2.
Q. Can New Zealand spinach be grown successfully in Louisiana?
A. Yes. New Zealand spinach is a low growing, ground cover type plant which usually preads to 3 to 5 feet across. It is similar to a bushy Amoranth and its flavor can be a little strong. New Zealand spinach should be started indoors in pest pots and set after all danger of frost in the spring. Young, tender stem tips and leaves can be harvested through the summer in most areas. It may reseed itself. Malabar spinach is a vining spinach substitute that may be preferred by some.
Q. What is Malabar spinach?
A. Malabar spinach, sometimes called summer spinach, is an attractive glossy leaved vine that grows rapidly during warm weather and generally produces edible leaves and shoots in about 70 to 80 days. Since it makes a vigorous vine, it should be trained against a fence or wall. Young leaves and growing tips can be harvested throughout the summer. Seed may be saved from the plant in the fall for replanting in the next garden. It is used fresh in salads or cooked as other greens. Both Malabar and New Zealand types are not a true spinach.
Q. My spinach foliage developed white, ruptured areas underneath the leaf and a faint yellow color on the upper side of the leaf.
A. This is White Rust and is caused by a fungus that causes severe loss of foliage. It is favored by cool, moist weather and can be controlled with foliar sprays of Maneb type fungicide. There are resistant varieties that should be used. Try varieties Hybrid 7 and Dixie Market if this problem causes much trouble.
Q. My spinach foliage has developed a bluish-gray material underneath the leaf. The leaves quickly dried up.
A. This is Blue Mold of spinach caused by a fungus. It is controlled with foliar sprays. Melody hybrid and winter Bloomsdale have a tolerance to B.M.
Q. White spots are developing on the upper side of the leaf which quickly fall out leaving the leaves with a very ragged appearance.
A. This is either Cercospora Leaf Spot or Anthracnose. These two fungal diseases attack spinach causing the described symptoms. A good fungicide program involving Maneb type fungicide will control both of these fungi.
Q. I planted my spinach this fall, yet the plants died soon after coming up.
A. In most cases, the soil temperature is too high and plants are being killed. It is best to plant spinach when the soil temperature reaches no higher than 75°F during the daytime. This can be determined by simply placing a soil thermometer in the upper one inch of the soil and reading it at noontime to determine the soil temperature. Also, once the plants become established, it is important to maintain a moisture level around it by light sprinkling periodically. Damping off or root rot may also be possibilities.
Q. Small, clear green or sometimes dark colored insects are a real problem on my spinach every year. How should I control them?
A. Any small clear-bodiced insects are more than likely aphids, often called plant lice by some gardeners. They are a problem to control in spinach because they get under the curled or crinkled leaf and are difficult to control unless spray applications are applied in large quantities of water with special attention to the underside of the leaves. Applications of a general purpose insecticide such as malathion begun early enough in the season generally gives adequate control. Aphids may also be washed off with a vigorous stream of water, but be sure to avoid damage to the plant.
Q. Each year my squash blooms profusely but seldom produces any squash to eat. What is wrong?
A. Squash plants produce both male and female blooms. For fruit set to occur, pollen must be transferred from the male to the female bloom. Pollinating insects (mostly bees) carry out this important job with the result being fresh squash for the kitchen. When treating the garden for insects and diseases, spray or dust during the late afternoon to avoid killing bees. Over fertility, starvation or extreme stress can limit the number of female blossoms. Long days may also change the sex expression of some squash.
Q. Most of the time my yellow squash is touch or has seed in the middle. What is wrong?
A. Squash is one of those crops which mature very rapidly requiring only 5-7 days from flowering to maturity in hot weather. The key to high quality is timely harvest, every other day in hot weather. Good yellow summer squash should be about 1-1/2 - 2 inches in diameter at the base and pale yellow in color. The tender skin should be easily nicked by the thumbnail. Squash which is dark yellow or yellow-orange with a firm rind is over mature. It should be removed from the plant and discarded. If over mature fruits are not removed, the plant will stop yielding.
Q. Will squash cross with other vine crops in my garden such as watermelons and cucumbers?
A. Generally, no. Squash will cross pollinate with some other types of squash and pumpkin such as yellow squash with green squash, but they generally will not cross pollinate with cucumbers, watermelons, or cantaloupes. This cross pollination will not result in offflavored or off-colored fruit from this year’s garden, but if seed are saved for planting next year, the result will be a combination of the parents. For example, if yellow squash crosses with a zucchini squash and you save seed, when you plant it out the result will have the characteristics of both parents.
Q. Can seed be saved from this year’s squash crop for planting in next year’s garden?
A. Yes, but this is not a recommended practice. Due to the fact that squash has both male and female blooms and that bees are necessary for pollination, a very strong chance exists that seed saved from this year’s crop will not breed true when planted next year. This is especially true if you are growing more than one type of squash. If you are only growing one type of squash and there are no other types of squash in the general area, then seed can be saved with a fairly high degree of genetic purity. If you are growing hybrid squash, seed should not be saved as hybrids will not breed true if saved and planted out.
Q. My squash vines are covered with a white, powdery substance on the leaves. The plants die rapidly.
A. This Powdery Mildew. It is a fungal disease that attacks squash causing rapid death of the plants. There are some varieties that have some tolerance to this. However, in all cases, a fungicide application will be required if squash is to be free of this disease. Powdery Mildew is a major problem in the fall of the year and is less of a problem in the spring. The material Benomyl, or Benlate, is the most effective fungicide at this time for the control of Powdery Mildew.
Q. My fruit blooms and sets young fruit, yet quickly become covered with a black, whiskery fungal growth.
A. This is Chaonephora fruit rot. It is a soil-borne disease which causes rotting of the young fruit. It is particularly damaging during extended wet periods. It can be controlled with a combination of treatments using foliar sprays of Chorothalonil, raised beds, and open foliage varieties. This allows air movement within the plant to dry out the soil. Also, avoid planting squash on heavy, poorly drained soils. Fungicide applications should be applied during wet periods to insure control at this dangerous time.
Q. My fruit, as it begins to develop, is covered with a white, moist appearing fungus.
A. This is Phythium, commonly called wet rot. It is controlled by growing the plant on a raised bed, planning in a well drained area, and improving air circulation around the plants as much as possible so that the fruit does not come in contact with the wet soil. Some squash will tend to produce their fruit in the upper part of the plant which helps reduce some of the damage.
Q. Each year my squash plants slowly wilt and die about the time they start producing. What could possibly be wrong?
A. Although squash is attacked by various types of insects and diseases which can cause death of the plant, more than likely your problem is squash vine borers. If this is indeed the problem, the white, grub-like, larvae can be found within the stem f the plant by cutting it open. The larvae are the result of eggs laid by a bright colored wasp-like moth on the foliage or stems of the plant. The eggs hatch and the larvae travel down the plant to the stem near the ground level and bore inside. Once inside, they feed in the stem and literally “core it out.” To prevent this problem control measures must begin about time the plants start to bloom by applying Sevin insecticide on the stem of the plant. Once the grubs are inside the stem of the squash plant it is almost impossible to control.
Q. How do I keep squash bugs from literally destroying my plants?
A. Squash bugs are very difficult to control especially if control measures begin when the insects have almost reached a mature stage. In order for control to be satisfactory, improved insecticides such as Sevin or Thiodan must be applied early in the season while the insects are small. Applications, whether using sprays or dusts, must be thorough and complete coverage provided. When utilizing these insecticides the materials must come in contact with the insect in order to be effective. Making certain the chemicals are applied to the base of the plant, underneath the foliage and in some cases underneath the stems of the plant itself will generally result in satisfactory control.
Q. Each year my yellow squash plants do a peculiar thing. Toward early to midsummer the plants which once produced yellow fruit start producing green or often times yellow and green fruit. This is generally accompanied by a twisting or mottling of the leaves. What could possibly be causing this problem?
A. Your plants have been affected by the virus diseases, most often Squash Mosaic Virus or Cucumber Mosaic virus. This virus is transmitted to your plants by insects which have been feeding on other virus-infected squash plants or perhaps some wild host plant. Once the plant gets this problem nothing can be done. Best control measures include insect control and planting varieties which will mature a crop early in the year. This problem is invariable more serious on late planted squash or summer planted squash than it is on the early spring planted crop.
Q. When should you bed out sweet potato roots for slip production?
A. To produce slips, sweet potato roots should be laid on their sides in hotbeds during February, about a month before the nighttime temperatures can be depended upon to stay about 60°F. The soil should be at least 70°F. Cover the sweet potato roots with 2 inches of moist sand and keep the hotbed between 75° and 80°F. When the sprouts develop, they should always be removed by cutting them off 4 inches above the soil line to reduce the transfer of pests.
Q. I want to grow a few rows of sweet potatoes in my garden? How do I get seed or plants?
A. Sweet potatoes are started vegetatively from transplants or vine cuttings rather than from seeds. Transplants, which are also called slips, usually grow from bedded roots. A vine cutting is obtained by cutting off a 10 to 12 inch section of a vine growing in the field. Local home gardeners should be encouraged to purchase slips or transplants.
Q. What causes sweet potato roots to be long and stringy rather than well shaped and of high quality?
A. This condition is generally caused by high fertility conditions. The edible portion of the sweet potato plant is a true storage root. Luxurious growing conditions resulting in vigorous vine growth will result in inadequate size of the storage root causing the edible portion to be poorly developed and stringy. A late planting will also produce long roots which may be more stringy.
Q. How do you know when sweet potatoes are mature and ready for harvesting?
A. Sweet potatoes can be harvested at any stage of maturity. They generally require from 95 to 140 days from planting to maturity depending upon variety. Sweet potatoes should be harvested before the first killing frost as cool conditions can result in physiological damage to the roots. Most people will prefer a medium sized root for home use. Thus a spot check of one or two hills will tell if they are large enough.
Q. How should sweet potatoes be handled after harvesting for long-term storage?
A. Fresh dug sweet potato roots should be handled like eggs. The skins are tender and bruise extremely easy. Any damage to the roots may cause considerable decay when placed in storage. After harvesting, protect from frost. Let the sweet potatoes dry for 2 to 3 hours then spread them out in baskets liked with newspaper. Place them in a humid area where the temperature will remain about 85°F for 10 days to 2 weeks. After this curing period, place them in an area where the temperatures will range from 55 to 60°F with a relative humidity of about 85 percent. Potatoes treated in such a manner will store well for several months. Remove any roots that show signs of deterioration of decay.
Q. Is there a real difference between sweet potatoes and those advertised as yams?
A. Yes and no. In areas of the south some sweet potatoes are advertised as yams, for example, Louisiana Yams. However, they are all sweet potatoes with the scientific name of Ipomea batatas. The true yam which is consumed in tropical areas is a totally unrelated plant with the scientific name Dioscorea batatas. The true yam is also called a Chinese Yam or Chinese Potato. True yams are not grown in the continental United States as food crops. The word yam that is associated with a true sweet potato is used to designate a sweet potato grown in the deep south where the roots will be more moist of flesh than those grown farther north.
Q. How do I control sweet potato weevils?
A. Utilization of certified weevil free “slips”, rotation and a good cleanup in the fall to remove all crop residue and weeds which might serve as winter hosts for the sweet potato weevil is the best current method of preventing weevil damage. Slips should always be harvested by cutting the vines 4 inches above the ground level and not by pulling. This greatly reduces insects and diseases that can be carried over with the slips. If chemical control is desired the seedbed can be dusted weekly with Thiodan. The seed potatoes can be dusted with 5% Imidan when stored to prevent weevil damage before budding.
Q. When I harvested my sweet potatoes, they were rough and the surface was cracked.
A. This can be caused by two things. One is uneven moisture levels within the soil, and the other is root know nematodes. If nematodes are suspected, check around the part of the root that was closest to the plant for small necrotic lesions in the potato itself. If nematodes are found, use the resistant variety Jewel in future plantings.
Q. After I dug my sweet potatoes, I found that as much as one half of the potato will be covered with a black, necrotic scab which decays rapidly.
A. This is Sweet Potato Scurf and is caused by a soil-borne fungus. It is best controlled by growing potatoes in acid soil. Also, the use of disease-free slips will help eliminate the disease. Crop rotation should also be followed.
Q. When should swiss chard be planted in my garden?
A. Since swiss chard is a close relative of beets, plant them the same time you do beets. Generally seeds should be planted two to three weeks before the average last killing frost in the spring. Seed can be sown for harvesting through the winter and most of the following year. Swiss chard is unusual in that quite often a single planting can be harvested for well over a year or perhaps into the second year if the flower stalks are removed as they develop.
Q. How should swiss chard be harvested?
A. Swiss chard is grown for its tender, vitamin enriched leaves. The plants generally grow to be one to two feet tall and the crinkled leaves have prominent central ribs. These ribs may be cut away from the rest of the leaves and cooked and served as asparagus. The remainder of the leaf is eaten as greens. For harvesting, cut the leaves off at the base of the plant with a sharp knife. The undisturbed inner leaves should continue to grow and should be ready for picking in a few days. Pick off and discard any old leaves. If they remain on the plant, production will be lessened.
Q. How is swiss chard used?
A. Both the leaves and the central leaf ribs are consumed. The stalks may be cut into two to three inch lengths and simmered in boiling, salted water until tender. They are generally served with butter and a touch of wine and vinegar. The leaves should be chopped coarsely and cooked quickly in just the water that clings to the leaves. They are often prepared with butter and salt. A favorite recipe for swiss chard involves serving the cooked greens in a hot bacon and wine/vinegar dressing sprinkled with shredded hard boiled eggs.
Q. When should I start my seed indoors in order to produce tomato transplants for setting out in my garden?
A. Depending upon temperature and how the plants are grown, it generally takes from 5 to 8 weeks to produce a healthy, 6-inch tall transplant for setting out in your garden. Five weeks in June-July and 8 during January-February. Cooler temperatures will slow growth and summer grown plants may normally be a little thinner due to heat. The plants should be grown in a warm area that receives plenty of sunlight or tall, poor quality, thin plants will result.
Q. When buying transplants at local nurseries or garden centers how do you select good ones?
A. First of all, make sure you select the right variety of transplant that is adapted and tested for your area. Secondly, look for plants that appear healthy uniformly dark green in color, and do not have any streaks, spots or holes in the leaves. The ideal tomato pepper or eggplant transplant should be just about as wide as it is tall. Avoid tall, spindly plants if at all possible.
Q. How often should be tomatoes be fertilized?
A. It is absolutely necessary to fertilize the garden before planting tomatoes. The next fertilizer application should be made when fruit set first occurs. From that point on, an additional light fertilization every two to three weeks is generally recommended. Plants grown on sandy soils should be fertilized more frequently than those being grown on heavy, clay-type soils. A general fertilizer recommendation would be one to two level tablespoons of a complete fertilizer scattered around the plant and worked or watered in. If using a fertilizer high in nitrogen such as ammonium sulfate, reduce the rate to about one level tablespoon per plant. For fall tomatoes, side-dress applications of fertilizer should cease 6 to 8 weeks prior to the first anticipated fall frost in order to hasten maturity of the fruit.
Q. Should tomato plants be staked, caged or left unsupported?
A. There is no doubt that tomatoes grown in Louisiana should be supported in some manner. Whether you cage or stake them is a matter of personal preference. Regardless of the method used, plants with foliage and fruit supported off the ground will out produce unsupported plants. Caging has several advantages. Caging involves much less work than staking. Once the cage is placed over the plant there is no further manipulation of the plant – no pruning, no tying. The fruits are simply harvested as they ripen. In many areas, staking and pruning of the plant to a single or multiple stem results in sunburn when the developing fruit is exposed to excessive sunlight. Other advantages of caging over staking include protection of fruit from bird damage by more vigorous foliage cover and less fruit rot. Staked plants should be allowed to bush out just before the extreme heat comes.
Q. My tomato plants look great. They are dark green, vigorous and healthy. However, flowers are not forming any fruit. What is the problem?
A. Several conditions can cause tomatoes to fail to set fruit. Too much nitrogen fertilizer, high nighttime temperatures (over 70°F), low temperatures (below 5o°F), irregular watering, insects such as thrips, and planting the wrong variety may result in poor fruit set. Any one of these by itself can cause poor fruit set and/or distorted fruit, but combinations can be even more damaging.
Q. Are there really low acid tomato varieties?
A. There are some varieties that are “slightly” less acidic than others, but for the most part this difference is so slight that no real difference occurs in taste or in how the tomatoes should be processed. Some of the yellow fruited types are slightly less acidic than the normal red varieties, but not enough to make any difference. Research conducted by the USDA has indicated that all the varieties currently available to the home gardeners are safe for water bath processing and the tangy quality of the fruit due to differences in acid content, but rather differences in sugar content.
Q. What does determinate mean and can you tell if a tomato is determinate by looking at it?
A. “Determinate” means that the plant will be short. Spring Giant and Bigset seldom are more than 5 to 6 feet tall. A determinate vine is distinguished by two leaves, a flower or fruiting cluster, two leaves, then a cluster, etc. As indeterminate vine has three or four leaves, then a cluster, three or four leaves, then a cluster, etc. A determinate vine grows and then loads up with fruit. The fruit ripening is more concentrated and the plant can only be grown for one season, i.e. Spring or Fall.
Q. Can I save seeds from my tomatoes from next seasons planting, and if so how is it done?
A. You can save seed from tomatoes if the variety is not a hybrid. Hybrid tomatoes such as Bigset and Spring Giant normally do not come true from saved seed. The plants and fruit from seed saved from your home garden probably won’t resemble the parent. Chances are that the fruit will be poorer quality and the vine characteristics will not be the same as the parent plant. However, for open pollinated varieties, such as Floradel, it is possible and easy to save seed. To save seed from tomatoes or any other home vegetable fruit type crops, leave the fruit on the plant until it is fully mature, pull the fruit and extract the seeds by crushing the pulp into a bucket of tepid water. Let this mixture ferment for 2 or 3 days. It is necessary to rinse the seeds two or three times to remove a germination inhibitor present in the fruit. After rinsing the seeds blot them dry and place them in the sun to dry. Store the seeds under cool, dry conditions.
Q. When caging tomatoes, how large should the cage be?
A. Experience has shown that the diameter of the cage should be at least 18 to 20 inches. Smaller cages often restrict plant growth and reduce yields. Height of the cage will vary but generally 2-1/2 feet is sufficient for most of the currently recommended varieties. However, if vining types are utilized, such as Better Boy, Homestead, Terrific, etc., then a cage 5 feet in diameter is preferred. Regardless of variety, the 2-1/2 foot tall cage is sufficient for most fall garden tomatoes. BE SURE CAGE WIRE HOLES ARE LARGE ENOUGH TO REACH THROUGH!
Q. How do you go about staking tomatoes?
A. Staking involves “pruning” or “suckering” the plant to either one or two main stalks. Tomatoes grown without support generally develop a sprawling bush shape. However, if the plant is to be trellised or staked, it must be pruned to a single or in some cases double stalk. The small suckers which develop between the axil of the leaf and the stem are removed in order to encourage the plant to develop a vine structure rather than a bush. A wooden stake generally an inch or so in diameter and six feet in length is driven into the ground beside the plant. Care should be taken not to damage the root system when inserting the stake in the ground. Therefore, do this shortly after transplanting. Position the stake on the opposite side of the flower cluster. The stalk of the plant is loosely attached to the stake as it grows. Attaching the plant to the stake can be done with twisties, soft string or in some cases strips of cloth. Sufficient support is generally provided if the plant is attached to the stake at 12- to 14-inch intervals. Suckering should be continued as the plant grows to prevent it from developing more than one or two central stems.
Q. What causes a tomato to crack and is there anything I can do to prevent it?
A. Cracking is a physiological disorder caused by soil moisture fluctuations. When the tomato reaches the mature green stage and the water supply to the plant is reduced or cut off, the tomato will begin to ripen. At this time, a cellophane-like wrapper around the outer surface of the tomato becomes thicker and more rigid in order to protect the tomato during and after harvest. If the water supply is restored after the ripening process begins, the plant will resume translocation of nutrients and moisture into the fruit. This will cause the fruit to enlarge, which in turn splits the wrapper around the fruit and results in cracking.
The single best control for cracking is to assure that the water supply is constant and regular. It is helpful to apply a layer of mulch at the base of the plant. This serves as a buffer and helps prevent soil moisture fluctuation. Water your plants thoroughly every week. This is especially important when the fruits are maturing. Some varieties are resistant to cracking, but unfortunately their yield and quality are generally less than other varieties.
Q. What could be causing the leaves of my tomatoes to turn brown along the edges?
A. Leaf-burn or scorch generally indicates some form of root injury, quite often in many home gardens caused by heavy amounts of fertilizer applied too near the roots of the plant. This injury often results in browning and die-back of the ends and margins of the leaves. Other possible causes of root injury due to herbicides, nematodes, insects or physical injury of roots by cultivation. Also overwatering or underwatering along with various types of diseases might cause leaf-tip burn as well as a potassium deficiency.
Q. About the time my tomatoes start to ripen and turn red, I lose at least half my crop due to bird damage. What can be done to prevent this problem?
A. Bird damage is common in all areas of Louisiana and gardeners will try almost anything to reduce or eliminate the problem. Scarecrows, aluminum strips, tin foil plates, and various types of noisemakers will work for a while until the local birds become accustomed to seeing these objects or hearing the various types of noises. One method which works quite well is to take old nylon stockings and cut them into pieces 10 to 12 inches long. Tie a knot in one end of the stocking and slip the open end over the entire cluster of tomatoes. Secure the end above the tomato luster with a rubber band or twistie. Birds will not be able to peck through the nylon stocking and your ripening tomatoes will be protected. Slip the stocking off the cluster and harvest the ripe fruit and replace it to protect later ripening fruit. Encourage bushiness of your plant to help hide the fruit.
Q. What causes tomato leaves to curl?
A. Leaf curl or especially distorted leaf shape quite often may be related to virus infection or sometimes chemical spray injury. However, in most cases this is not the case. The exact cause of this “tomato leafroll” is not fully known. Tomato leafroll generally starts to show up about the time of fruit setting. The tomato plants begin to show an upward rolling of the leaflets of the older leaves on the lower half of the plant. This gives the leaflets a cupped appearance with sometimes even the margins touching or overlapping. The overall growth of the plant does not seem to be greatly affected and, in general, yields are about normal. This condition appears to be more common on staked and pruned plants than on those that are not. It seems to be common when excessive rainfall or overwatering keeps the soil too wet for too long a period. It also seems to be related to intensive sunlight which causes an accumulation of carbohydrates in the leaves. Some varieties of tomatoes, such as the TAMU Saladette and Monte Grande are characteristically curled due to genetic causes.
Q. What causes some of my early tomato fruit from the spring garden to be oddly shaped and generally of poor quality?
A. This condition is usually caused by low temperatures during bloom and pollination. Fruit that sets when temperatures are 55°F or below often are odd-shaped and of poor quality. The blooms that these tomatoes develop from often were abnormal due to these temperature conditions which result in abnormal, odd-shaped fruit with very little seed.
Q. Do products which aid in tomatoes setting such as “Tomato Set” really work and if they do, how should they be used?
A. These products are hormonal in nature and designed to take the place of natural pollination. Unfortunately, they do not work as well as the manufacturers describe. Tomato set will actually work better when tomatoes are failing to set because of too cool temperatures rather than because temperatures are too high. Most of the problems we have in Louisiana with regard to poor fruit set in tomatoes is due to high temperatures rather than low temperatures. Also, whatever tomatoes set due to the use of these products are generally puffy and seedless resulting in unsatisfactory, poor quality fruit.
Q. What is the plant sold in many garden books and advertised as a “tree tomato?”
A. The plant currently being advertised as a “tree tomato” is a member of the Nightshade family. The regular tomato also belongs to the same plant family but is a different species. The tree tomato has the scientific name Cyphomandra crassifloia. Like the true tomato, it is a native of Peru. It is commonly grown in market gardens in that country and in several subtropical countries including Brazil and New Zealand. The tree tomato is woody, grows from 8 to 10 feet tall and does not bear fruit until 2 years after seeding and may continue to bear for 5 to 6 years. They are not winter hardy except in coastal Louisiana and would need to be taken inside over winter. Fruits of the tree tomato are oval in shape, about 2 inches long and change from greenish purple to reddish purple when fully ripe. The fruits are low in acid, and the flavor is moderately agreeable. Some varieties of the tomato produce bright, red fruits. The fruits may be used in stew or preserves after the tough skin and hard seeds are removed.
Q. Should you allow tomatoes to become fully ripe and red on the vine before harvesting?
A. Generally, yields will be increased by harvesting the fruit at first blush of pink rather than leaving them on the plant to fully ripen. Contrary to popular belief, a tomato picked at first sign of color and ripened at room temperature will be just as tasty as those left to fully mature on the vine. Another advantage of picking tomatoes before they turn full red is that damage from birds, insects, and fruit cracking will be lessened.
Q. If tomatoes are picked green or before they are fully mature, how should they be handled to insure proper ripening and full flavor?
A. Tomatoes picked immature should never be refrigerated. They should be placed in a single layer and exposed to indirect sunlight at room temperature. When they are fully ripe, they should be placed in the refrigerator where they will store for several weeks. Those handled in this manner will be of quality and full flavor.
Q. What is a husk tomato?
A. Husk tomato is also called Ground Cherry, Poha Berry or Strawberry Tomato. It is grown the same way as tomatoes and produces a fruit about the size of a cherry tomato. The fruits are produced inside a paper-like husk which when ripe, turns brown, and the fruit drops from the plant. If left in the husk, it will keep for several weeks. Like the tomato, they are sensitive to cold weather and should be set out from plants after all danger of frost in the spring. Space the plants about 1-1/2 feet apart in rows at least 3 feet apart. When ripe the small fruit can be used in pies, jams or may be dried in sugar and used like raisins.
Q. I have the best tomato crop I have ever had, but the large tomatoes are falling off. Even he ones that stay on the vine are jarred off easily. What is the problem?
A. Cool fall temperatures cause the abscission zone (where the tomato is attached to the plant) to weaken, and the heavy fruit subsequently falls off. Gather fallen tomatoes as soon as possible, wipe clean and store in a warm place so ripening will occur. Those aborted tomatoes will rot if left on the ground.
Q. I have large translucent areas on my tomato fruit. What’s going on? Is this a variety flaw?
A. Your problem is not a varietal origin; it is an environmental problem. The translucent areas are sun scalds. Heat destroys the color pigments of the tomato when exposed to direct, intense sunlight. This damage does not make the tomato inedible. Damage hould show on the outside shoulder where the sun strikes the fruit.
Q. What about propagating tomatoes for the fall garden from existing vines?
A. If necessary, use suckers or layering (cover with soil until roots appear) of existing vine. Do this several weeks before the recommended transplanting date for fall tomatoes, and be sure to use early tomato varieties that are presently free from virus.
Q. Can spring planted tomatoes be cut back in late summer or early fall resulting in renewed growth and increased production until the first killing frost?
A. This can be done in some areas of Louisiana, especially in the central and southern parts of the State. However, make certain that the plants are of an indeterminate variety, healthy and free of disease problems. Trying to carry an unhealthy plant through the summer into the fall usually means disaster. If the plants are to be cut back, avoid removing too much of the foliage as hot weather conditions can result in the plant literally burning to death. After the pruning operation additional fertilizer and water should be applied to encourage renewed growth and hopefully increase tomato production well into the fall.
Q. How do you tell when a green tomato harvested early to prevent freeze damage will ever turn red and ripen?
A. This can simply be done by utilizing a sharp kitchen knife. Harvest a tomato that is typical for the majority of green tomatoes on your plants. Look at size but pay particular attention to fruit color. Take a sharp kitchen knife and slice through the tomato at its center. Closely examine the seed within the fruit. If the seed is mature enough and consequently hard enough to move out of the way of the sharp knife, then given sufficient time that fruit will eventually turn red and ripen. If the seed are cut by the sharp knife than those fruit will never properly ripen. Compare the color and size of the tested fruit when harvesting those on your plants. The majority of those fruit which are of similar color and size will eventually ripen and turn red. If the fruit’s blossom end shows a whitish star radiating from its center point, then it should be ‘mature green.’
Q. My tomato foliage is infected by irregularly shaped spots which cause the foliage to turn yellow and defoliate. It has occurred in all seasons and is found on both the top and bottom leaves.
A. There are a number of leaf spots that will attack tomatoes. Septoria Leaf Spot and Early Blight are seen quite often in Louisiana. They can be controlled with a Maneb plus Zinc spray program. It is important that you begin the spray program early in the life of the plant to insure complete protection.
Q. My tomato plants appear as if a hormone type herbicide has been sprayed around them, causing the leaves to become distorted.
A. This is a virus and is called Tobacco Mosaic Virus. If the virus is extremely severe, the plants should be removed to prevent further spread to other plants. While working around the infected plants, the virus can be spread to nearby healthy plants. Many of the viruses are insect transmitted, so it is important that you carry out a good insect control (esp. thrips) program on tomatoes
Q. My tomato plants are stunted and have a pale yellow foliage. The root system has knots or swellings on the roots.
A. This is root knot nematodes. The use of resistant varieties such as Terrific, Pelican Bigset, Bonus, Better Boy, and Small Fry will help eliminate this problem. If other varieties are to be grown that are not nematode resistant, then soil fumigation with Vapam is required. It is best to use only nematode resistant varieties. Nematode resistance is indicated by the letter N after the name. Example: Terrific VFN.
Q. My tomatoes were healthy during the spring and early summer, yet after a recent rain, they wilted and died very rapidly. I found a white fungal growth at the base of the plant.
A. This is Southern Blight. It is a soil-borne fungus and lives on organic material in the soil. The use of Terraclor as a preplant treatment will help reduce this problem. Also, the deep burial of undecomposed organic material in the soil will help reduce the problem. It is important that you control foliage diseases on tomato plants as the falling leaves around the base of the plant will act as a source of food for the fungus, and it will built up in this area and cause damage later. Crop rotation will also help eliminate this problem to some extent.
Q. My tomato plants wilted rapidly. On examination I found no galls or white mycelia matter around the base of it, but when I cut the stem open, I found that the stem had a brown ring around the inside.
A. This is Fusarium Wilt. It is a soil-borne fungus that attacks tomatoes and other crops. It is controlled only through the use of resistant varieties. Most commercial tomato varieties now have resistance to this. It is important, however, that before you plant a variety, you make sure that it is resistant to Fusarium Wilt. This resistance is denoted by the letter F after the name. Example: Terrific VFN.
Q. What do the letters “VFN” often found associated with particular tomato varieties indicate?
A. These letters should be very important to gardeners in all areas of the state. VFN indicates that this particular tomato variety is resistant to three types of diseases; Verticlum wilt, Fusasium silt, and nematodes. Many of the new hybrid varieties are VFN types. Varieties possessing this type of disease resistance are preferred in many areas of Louisiana where many of these problems are severe and cause great losses to home gardeners. F and N resistance are considered most important here.
Q. The lower foliage on my tomatoes is beginning to turn yellow and drop. The leaves have circular, dark brown to black spots.
A. This is Alternaria Leaf Spot. It is a common problem on tomatoes and causes defoliation, generally during periods of high rainfall. Tomatoes should be planted on a raised bed to improve water drainage. They should be grown with enough space between them so that air movement can occur and thus dry the foliage out and help prevent diseases. Follow a spray program using Maneb, Captan, or Chlorothalonil beginning when the fruit is set and continuing at 1- to 2-week intervals during the growing season.
Q. My tomato fruit have small yellow specks on their surface. When peeled, those yellow specks form a tough spot which must be cut off before eating the tomatoes. What’s wrong?
A. Your problem is not of a varietal origin. The yellow speckling which you are seeing is caused by the sucking of stinkbugs. Early control of sucking insects which feed on the fruit is necessary if this problem is to be avoided. Use Sevin or Thiodan.
Q. We planted tomatoes in our small garden. They are loaded and are the best tomatoes we have ever had; however, there are some small holes near the stem end of the tomato. When we cut the tomato open, there is a small worm inside. What is it and what can we do?
A. You have been invaded by the Tomato Pinworm. They usually do not damage the fruit until the infestation is quite severe. They normally show up on the leaves first. They can be controlled only by a preventive insecticide spray every 7 to 10 days. When the damage is evident, it is too late to do anything about it.
Q. What Causes turnips to fail to make large roots?
A. Like radishes and other bulbing crops, if left too crowded turnips will fail to enlarge. Turnips also require a moderately fertile soil and adequate moisture in order to make large, fleshy roots. For good size bulbs, turnips should be spaced 2 to 3 inches apart. Planting should occur as soon as the ground can be worked in the spring. For a fall crop, planting should begin when daytime temperatures average below 80°F. In many areas of Louisiana, planting can begin in early fall and continue until about 5 to 6 weeks before maximum daytime temperatures average 80°F.
Q. Are there varieties of turnips grown just for the tops and not their enlarged roots?
A. Yes. The varieties Sevin Top and Shogoin are grown primarily for their tops and usually fail to make large, high-quality roots.
Q. What causes my turnip greens to often have a bitter and pungent flavor?
A. Conditions which result in slow growth or stress of the turnip plant will often cause the
leaves to have a bitter, off-flavor. This condition is most prevalent when turnip leaves mature under relatively high temperatures in combination with unfavorable growing conditions.
Q. My plants appear to be stunted, and after examining the roots, I found small, round galls.
A. This is root knot nematodes. They are controlled by rotation, summer fallowing, and hemical treatment with Vapam.
Q. I recently harvested my turnips and found the root to be black in the center.
A. This most often is the result of Boron deficiency. To be sure of the exact problem, a soil sample should be sent to the Soil Testing Laboratory at LSU. Note: Refer to MUSTARD for other diseases which are associated with turnips.
Q. How do you control aphids or plant lice on turnips?
A. Aphids can sometimes be a real problem, but generally can be easily controlled if applications of an insecticide such as Malathion are begun early. Applications should begin the first time the insects are observed and applications made periodically to maintain satisfactory control.