Cooperative Extension Service 
Institute of Food and Agricultural Sciences
Hendry County Extension P. O. Box 68 LaBelle, Florida 33975-0068 Phone (863) 674-4092

Hendry County Horticulture News

Disease Control - Cultural Practices are Important In Control Too

Harmful insects and some of the other pests that attack fruits and vegetables generally can be detected with the unaided eye.  But most disease organisms are too small to be seen even with a magnifying glass. Unless you have a microscope, you may never get a close-up look at the fungus that causes early blight of tomatoes or any of the other disease pests that are often limiting factors in fruit, flower and vegetable production.

Because disease pests are so small, most home gardeners tend to ignore them or underestimate their importance and may not know much about them.  Consequently, more emphasis is often placed on insect and weed control, and gardeners sometimes fail to carry out an effective disease control program.  Although disease pests may attack  your garden, they don't have to wreck your plantings.  Many people believe that control of plant diseases always mean the use of chemicals, but many diseases can be controlled by cultural practices.

Selection of plant material will greatly affect the amount of disease problems.  Some plants are very susceptible to diseases while others have very few, if any, disease problems.  The use of native plants can reduce the incidence of plant diseases.

Some diseases such as powdery mildews and botrytis flower blights are encouraged by high humidity in plantings.  Losses can be reduced by not crowding plants.  Thin the plants to permit free air circulation and allow sunlight to reach the lower parts of the plants and soil.

Diseased branches and shoots on trees and shrubs should be removed and discarded before a disease can spread.  In routine pruning, always remove diseased or unthrifty growth first and then prune to develop and shape the tree or shrub.  Be sure to sanitize pruners after removing diseased material.

Many disease organisms carry over from one season to the next on fallen leaves.  It is advisable to collect and dispose of diseased foliage.  Do not include diseased material in the compost heap because of the danger of survival of disease organisms and subsequent spread.

The maintenance of a balanced fertilizer and water program generally produces plants which have some resistance to plant diseases.  Some diseases such as certain cankers are more prevalent on plants that are nutrient deficient or suffering from drought.  However, other diseases such as rusts and powdery mildews are more severe on succulent growth. High fertilizer content, especially nitrogen, and abundant moisture will favor these diseases.  Excess soil moisture or moisture stress may also lead to root rot problems.

When a disease problem develops in a planting, particularly of annuals or succulent perennials, the gardener should consider moving the planting to a new location.  This is the same as crop rotation that is commonly practiced by farmers.  It permits the plants to grow in soil relatively free of disease organisms and also hastens the natural decline of these disease organisms in soil where they have built up because of the growth of susceptible plants.

Plant in a location suitable for the plant.  Don't put shade loving plants in exposed situations or sun loving plants in the shade.  Also, avoid extremely wet or dry locations unless plants are suited to these conditions.  Many root diseases are favored by wet soils. Creating good drainage may reduce the severity of these diseases.

Plant at the most suitable time of the year to ensure survival and good growth of the plant.  Check with the Hendry County Extension Office or local nursery as to the best planting time for various plants.

Despite your best efforts there are times when chemical applications may be necessary to combat disease problems in the landscape.  This is particularly true when environmental conditions like excessive humidity and rainfall or high populations of insect vectors conducive to the development of diseases are present.  Check with the Hendry County Extension Office for tips on ways to keep diseases under control.   Good luck and good gardening.

Gene McAvoy is the horticulture agent with the Hendry County Extension Service.  Direct your horticulture questions to PO Box 68, LaBelle, FL 33975,  e-mail - or phone 863-674-4092 or  863-983-1598.  You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle.   Office hours are from 8:00 - 5:00.

The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity - Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.

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