Vegetable Press

Vol. 00 No. 12 December 6, 2000

New At Truck Crops

Dr. Bill Evans, Research Coordinator

I want to take this opportunity to introduce myself to the Mississippi vegetable industry and those readers serving the industry. My name is Dr. William B. Evans (Bill). I started in late August as the Research Coordinator/ Assistant Horticulturist at the MAFES Truck Crops Branch in Crystal Springs. I came to Mississippi from the Muck Crops Branch of The Ohio State University. There, I managed a 15 acre station in the heart of 5,000 acres of commercial vegetable crop production.

Crops I've worked with include all of the tomato and squash family crops, snap beans and southernpeas, lettuce, greens, carrots, corn, and radishes. I've also worked with some rarer ones like parsley, cilantro, dill, and celery. I will share some of my experiences with you at the Tri-State meeting in Biloxi in February (see calendar at end).

As Research Coordinator at the Truck Crops Branch, I oversee activities at the Crystal Springs site, as well as the Beaumont unit, our 15 acre site southeast of Hattiesburg. As Assistant Horticulturist, I am charged with conducting research that benefits Mississippi while advancing agricultural science. My areas of interest include soil fertility, mineral nutrition, the influence of production practices on crop quality, organic amendments such as manures and cottonseed hulls, and developing programs supporting larger producers and smaller, part-time growers.

I would appreciate any comments and suggestions from growers and extension personnel that might help me serve the vegetable industry. I need your help in learning what current and future challenges are facing the industry, and how my research program might address these problems. Please feel free to call (601) 892-3731 or e-mail me (wbe1@ra.msstate.edu) any time. I look forward to meeting and working with all of you.

New All- America Selections Winners

Dr. Rick Snyder
Vegetable Specialist

{note: information from this article is taken from the National Gardens Bureau newsletter. More information is available from their web site at www.all-americaselections.org }

All-America Selections is a national, non-profit organization which recognizes some of the best new varieties by assigning then an award. This award comes only after testing by judges at all of the 23 testing sites in North America. The Truck Crops Experiment Station in Crystal Springs, MS is one of these testing sites. Following are the newest winners of the prestigious All-America Selections award.

'Honey Select' sweet corn has proven its delicious sweet honey flavor and tender eating quality in trials across North America. The only reason to grow your own sweet corn is flavor and 'Honey Select' has flavor and ease of growing. A TripleSweet™ variety, 'Honey Select' ears are 75% sugary enhanced (se) and 25% supersweet (sh2) kernels. Unlike other supersweet types, 'Honey Select' does not require isolation from other corn pollen. Maturing in about 79 days, growers will find yellow 'Honey Select' ears about 8 inches long. Mature ears can be harvested over a longer time without loss of eating quality.

'Giant Marconi' is an improved Italian grilling pepper. About 6 to 8 inches long, the tapered green pepper will mature to red on the 30-inch plant. 'Giant Marconi' tastes excellent raw but is best when grilled. It has a memorable sweet, smoky flavor. 'Giant Marconi' was judged best in its class for earliness, yield, pepper size and flavor. Plants are resistant to Potato Virus Y and Tobacco Mosaic Virus, which means the plants tend to live longer for an improved yield. Green peppers can be harvested in about 72 days from transplanting.

'Jolly' is a delicious, new pink tomato. The vigorous indeterminate vines produce abundant clusters of 1_ ounce peach shaped fruit. Growers can expect 9 to 14 tomatoes per cluster. 'Jolly' plants yield ripe fruit in about 70-75 days from transplanting. 'Jolly' will produce the highest quality tomatoes if vines are pruned and tied to vertical support. 'Jolly' plants are easy-to-grow offering meaty, sweet, pink tomatoes fresh from your garden.

'Super Star' is an improved white sweet onion recommended for all spring gardens in North America because it is day length neutral. Most onions require long days - (over 12 hours of sunlight) or short days to bulb. 'Super Star' does not have this requirement so it is widely adaptable. If seed is sown and transplanted early, 'Super Star' onions can weigh one pound or more, when mature in about 100 days. Resistant to pink root, 'Super Star' onions are exceptional when eaten raw, in salads or sandwiches. 'Super Star' is milder, sweeter and larger than 'White Sweet Spanish' the closest comparison.

Greenhouse Aphid Control

Dr. J. Pat Harris,
Extension Entomologist

Aphids (plant lice) are small, soft-bodied insects that vary in color from pink to yellow to orange or black. They suck plant juices causing leaves to curl and turn yellow. They may also inject poisonous saliva or disease-causing organisms during feeding. They may cause a failure of bloom set in some vegetable crops. These insects secrete "honeydew" that harbors sooty mold fungus which can further spoil tomatoes. Aphid-borne virus infection from surrounding vegetation and gardens is a major reason for yield reduction in the fall. Care must be taken to eliminate aphids and other insects close to the greenhouse (at least 100 feet). Control them by using spray applications of malathion, thiodan, pyrellin, or M-pede 49 EC. Refer to individual product labels for crop registration, rates, usages, and precautions.

Control of Leaf Feeding Caterpillars

Dr. J. Pat Harris,
Extension Entomologist

Leaf feeding caterpillars, including loopers, imported cabbage worms, and diamondback moth larvae infest a number of our leafy vegetable crops. These include broccoli, cabbage, cauliflower, collards, mustard, and turnips.

Loopers are pale green "measuring" worms with only two pairs of prolegs. They have light colored stripes down their backs and are up to 1 inch long. They are one of the more difficult caterpillars to control. Imported cabbage worms are velvety green in color and may measure up to 1 1/4 inches long. They feed primarily on the underside of leaves, producing ragged holes, and bore into cabbage heads. Diamondback moth larvae may be hard to find. They feed on the underside of leaves of older plants and in the buds of young plants. They are greenish or cream colored and about 3/8 inch long. When disturbed, the larvae will hang suspended by a silk strand. This insect can be very difficult to control, especially where resistance problems exist.

Loopers, imported cabbage worms, and diamondback moth larvae feeding on broccoli, cabbage, or cauliflower may be controlled with label rates of *Lannate 1.8 SL, *Pounce 3.2 EC, *Ambush 2 EC, Endosulfan 3 EC, Endosulfan 50 WP, or formulations of Bacillus thuringiensis (B.T.) (e.g., dipel, thuricide, javelin, cutlass, etc.). Directed sprays (drop nozzles) applying 25-40 gallons of water per acre should be adequate for coverage. If larvae are difficult to control, mix B.T. with one of the other recommended materials at label rates and apply to foliage.

Loopers, imported cabbage worms, and diamondback moth larvae feeding on collards may be controlled with label rates of *Lannate 1.8 SL, *Methyl Parathion 4 EC, Endosulfan 3 EC, Endosulfan 50 WP, or formulations of Bacillus thuringiensis.

Loopers and imported cabbage worms feeding on mustard and turnips may be controlled with label rates of *Lannate 1.8 SL, Malathion 5 EC, and formulations of Bacillus thuringiensis. For best control, apply when worms are small.

Spreader-stickers added to spray will be helpful with control of insects attacking vegetables with waxy leaves. Timing and coverage of insecticide sprays are the two most important factors in controlling insects attacking vegetables. Refer to labels for rates, usages, and precautions.

*Restricted pesticides

Outside Cold Increases Greenhouse Humidity: More Disease Problems

Dr. Alan Henn,
Extension Plant Pathologist

{editor's note: Dr. Henn is a new Extension Plant Pathologist located at Mississippi State University in Starkville.}

Greenhouse plants are busy growing this time of year. Part of plant growth is transpiration - the release of water vapor into the air. In the late afternoon the greenhouse air cools and cool air holds less moisture than warm air. That moisture has to go someplace - and in the process of doing so, the humidity levels will rise, even to levels greater than 90%.

Moisture released by the cooling air not only increases the relative humidity of the air, but deposits free water on surfaces in the greenhouse - including plant leaves. This condensation is most noticeable, however, on colder surfaces, such as the on external plastic cover which is below the dew point - the temperature at which the air becomes saturated with water.

High humidities and free water are great conditions for many plant diseases to flourish. This is not so great for the bottom line. Fungal diseases which may be a problem in these conditions include gray mold, target spot, leaf mold, and timber rot.

Gray mold is caused by the fungus Botrytis cinerea. The free moisture on the leaves and relatively cool temperatures (18-23 C or 64- 73 F) provide conditions needed for the spores to germinate. Once germinated, infection follows in as little as 8 to 12 hours. The fungus grows through the tissue, which may then produce the characteristic symptom, a fuzzy greyish to brown almost velvet-like appearance. This "velvet" is actually produced by the fungal reproductive structures.

Infection can occur on all above ground portions of the plant but dead or dying leaves or flower petals are especially susceptible. Once enough sporophores have been produced in the dead and dying tissue, other tissue may be directly invaded.

Target Spot is another fungal disease. Caused by the fungus Corynespora the disease produces leaf symptoms similar to the early blight fungus (Alternaria). All above ground parts of the plant may be attacked. Fruit lesions may be a problem.

Given the cooler temperatures, early blight may not be a problem. Plenty of inoculum (spores which can infect the plants) seem to be available throughout the state, so the disease bears watching.

The fungal disease Leaf Mold (Fulvia fulva) generally affects foliage. It is not a very common disease because many greenhouse tomato varieties have some resistance. Symptoms are a pale green to yellow flecking of the upper surface of the leaves. When the leaf is turned over, a greenish mold may be associated with the colored areas.

Timber rot is caused by Sclerotinia sclerotiorum. This fungal disease will be more common in greenhouses which have been infected in the past. Without careful removal of the diseased vines, the hard resting structures which were produced inside the stem will fall out. Some will be located in an area where they can germinate and produce spores. Infection usually occurs where fallen flower petals have lodged or in leaf axils. The growing fungi produce water soaked areas in the stem which become soft and eventually turn a bleached, white or grey when they dry. Infected fruit is gray and goes to a rapid watery rot.

Prevention is the best management for these diseases. Scout your greenhouse regularly. Keep the air inside the greenhouse moving, reduce free water and lower the relative humidity.

Free water may be reduced by not watering the foliage and by reducing the humidity so that cooler night time temperatures will not condense water from the air.

Relative humidity may be reduced by periodically introducing cool, low humidity, outside air into the greenhouse and allowing the heaters to warm it up. This may need to be done several times in the night as well as in the late afternoon.

Keep the air circulating inside the greenhouse, especially in the lower plant canopy. This will reduce the chances for cool spots and disease development. If you do find infected plant parts, place them in a plastic bag to prevent spreading the spores and remove them from the greenhouse.

The fungicide Exotherm Termil will help you keep ahead of all but timber rot. Follow label directions. Management of timber rot is by immediate removal of infected tissue.

Calendar of Coming Events

Dr. Rick Snyder,
Vegetable Specialist

December 11-13 - 15th Annual Southeast Vegetable and Fruit Expo and Ag Tech 2000, at Sheraton Greensboro Hotel Four Seasons, Greensboro, NC. For information, contact Allan Thornton at (910) 592-7161, email to allan_thornton@ncsu.edu, or check the web site at www.soil.ncsu.edu/agtech2000.

February 14-16, 2001 - Tri-State Ark-La-Miss Fruit and Vegetable Growers Meeting, at the President Casino Broadwater Towers Hotel in Biloxi, Mississippi.. For information, contact Dr. John Braswell at (601) 795-4525, fax (601) 795-0653, or email braswell@ext.msstate.edu.

March 21-23, 2001 - North Central Small Farm Workshop, "Small Farms: A Renewed Opportunity" ; at Campus of University of Illinois - Springfield. Please register on-line at: www.aces.uiuc.edu/~asap/smallfarm/registration.html . For more information, contact Debi Kelly, MO Alternatives Center, 573-882-1905, or e-mail kellyd@umsystem.edu.

Dr. Richard G. Snyder

Vegetable Specialist

Truck Crops Research & Extension Center

Mississippi State University

P.O. Box 231

Crystal Springs, MS 39059

PHONE: _ (601) 892-3731

Fax: (601) 892-2056

Email: RickS@ext.msstate.edu

Web Pages

Central Mississippi Research & Extension Center
http://www.msstate.edu/dept/cmrec/

North Mississippi Research & Extension Center
http://www.msstate.edu/dept/nmrec/

Greenhouse Tomato FAQ
http://ext.msstate.edu/anr/plantsoil/vegfruit/tomato/ghtomato/faq.html

Vegetable Resource Page
http://www2.msstate.edu/~ricks/

Organic Fruit and Vegetable Web Page
http://www.msstate.edu/dept/cmrec/organic/

Greenhouse Tomato Short Course
http://www.msstate.edu/dept/cmrec/GHSC.htm

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