VEGETABLE DISEASE MANAGEMENT

           Pat Donald, Research Assistant Professor     
                         (573) 882-2716
           Om Sehgal, Professor of Plant Pathology
                         (573) 882-7060
                 University of Missouri-Columbia

     Gardeners can be proud of the efficiency of vegetable production. A
relatively small area provides a significant harvest of nutritious vegetables
to be eaten fresh, canned, or frozen.
     Gardening - commercial or amateur - can be a paying proposition.
Control of diseases caused by parasitic bacteria, fungi, viruses, mycoplasmas
and nematodes is important.  Consideration should be given to some basic
principles to avoid costly and discouraging losses from diseases.
     Prevention should be the first priority in integrated disease control.

USE DISEASE-FREE SEED OR PLANTS
     ùPurchase seed or plants from reliable dealers who pay attention to
disease prevention.
     ùUse a protective seed treatment fungicide. Fungicides applied
to the seed before planting will protect against seed rot and damping-off.
Captan and thiram are common seed treatment protectants.
     ùUse hot water seed treatment for certain vegetable seeds, such as
crucifer seed and tomato seed. Seed is treated at 122 degrees F for 20 to
25 minutes, depending upon the kind of vegetable. Exact temperature and time
is very important. After the hot water treatment, treat seed with fungicide.

USE KNOWN DISEASE-RESISTANT VARIETIES
     ùCertain varieties of vegetables are resistant to one or more disease
agents. This built in protection is the most desirable means.  For example,
certain tomato varieties are resistant to one or more serious diseases,
classified as VF, VFN, VFNT, VFNTA (V = Verticillium wilt resistant,
F = Fusarium wilt resistant; N = root-knot nematode resistant,
T = tobacco mosaic virus resistant, A = Alternaria or early blight resistant).
     ùWhen you buy plants, look for these classifications. Take advantage of
this whenever possible.

PRACTICE CROP ROTATION IN THE GARDEN
     ùAvoid planting the same or related vegetable species in the same place
year after year.
     ùCrucifer species (broccoli, Brussels sprouts, cabbage, cauliflower,
collards, kale, turnip) are susceptible to certain common disease agents
that can be harbored on the surface of the soil or in the soil.
     ùCucurbit species (cucumber, melons, pumpkin, squash) are susceptible
to certain common diseases that build up in the soil or remain in residues
on the surface.
     ùSolanaceous species (egg plant, pepper, potato, tomato) share
certain soil-borne fungae and bacterial pathogens.

PRACTICE SANITATION IN AND NEAR THE GARDEN
     ùClean up, burn, or compost all diseased plants and residues, especially
at the end of the season.
     ùGeneral reduction of plant residues in and around the garden area will
help to reduce the incidence of several vegetable diseases.

CONTROL WEEDS IN AND NEAR THE GARDEN
     ùWeed control not only reduces competition for water and nutrients,
but it also helps to remove sources of infection. Many weeds are hosts to
the same diseases as vegetables.
     ùDestroy weeds with appropriate herbicides or mechanically when they
are young for most effective control.

ENCOURAGE A PRODUCTIVE ENVIRONMENT
     ùHealthy, vigorous vegetable plants are less susceptible to disease
attacks, usually.

USE PROPER CHEMICAL TREATMENTS 
     ùBe sure to select fungicides labeled for vegetables. Some commonly
used fungicides are benomyl (Benlate), chlorothalonil (Bravo 500, 720, 90 DG)
fixed or neutral copper (Kocide etc.), mancozeb* (Dithane DF, Manzate 200 DF
or Penncozeb DF).
* Label changes in several of these fungicides have been made that have
removed many uses from vegetables. Read the label before using.  There are
significant price differences between some of the registered pesticides.
     ùBe sure to read the label on all chemicals for directions and
precautions. Label changes have occurred with several of the foliar fungicides
that have been standard treatments for vegetables for many years. It may be
permissible to use up materials with the old labels providing there are no
specific cancellations by the E.P.A. that would prohibit use.
     ùFor most diseases, the fungicide spray application should be started
early, before you observe disease symptoms. For better control, repeat at
10-14 day intervals.
     ùBe sure to observe the time interval between the last application and
harvest as indicated on the label.
     ùApply appropriate insecticides to control insects. There are many
insects that are carriers of diseases, such as Bacterial wilt of cucurbits
by cucumber beetles and viruses of beans, cucumbers, tomatoes and other
vegetables by aphids.

     For more information, refer to Knott's Handbook for Vegetable Growers,
John Wiley and Sons; MU publication G6202, Disease Prevention in Home
Vegetable Gardens; and MX384, Midwest Vegetable Production Guide for
Commercial Growers.