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Vigor a Key to Disease-free Garden Growing healthy, vigorous plants is the key to producing quality fruits and vegetables. Plant diseases can kill garden plants, reduce yields, or cause unsightly blemishes on produce. By practicing a few basic gardening principles, you not only will improve the quality of your produce, but also will reduce the need for chemical sprays. Thinking about the needs of your plants is the first and most important factor to consider before planting your garden. Extension publications often will help you determine those needs. Plants vary in their requirements for sunlight, soil conditions, and irrigation. To keep plants healthy and productive, it is important that you understand and meet these needs. Enlarge photo A soil test can help you determine how much fertilizer to add. Fertilizing too little or too much can make plants more susceptible to disease. Choosing the right location for your garden is critical. (See story on site selection.) Most vegetables prefer sunny locations with little or no shade. Consider moving your garden if it is located in partial shade, or prune overhanging tree branches to provide the needed sunshine. Generally speaking, the more sun, the better. Since plants convert sunshine to starches and sugars, plants grown in full sun will produce larger vegetables and sweeter fruit than those grown in partial shade. In addition, sunshine helps dry out wet foliage, thus reducing the potential for disease problems. Proper soil conditions are equally important to the health and vigor of plants. Most plants prefer a loam soil with good water drainage. Avoid low-lying areas where water collects, since damp conditions promote root rot. You can improve any soil by adding organic matter such as compost or peat moss. This is especially true of sandy and clay soils. Organic matter helps sandy soils hold water and nutrients. It provides clay soils with more air spaces so that roots can breathe more easily. (See story on soil improvement.) Some plants, such as blueberries, prefer an acid soil, but generally a pH of 6 to 7 is ideal for most plants. A soil test kit purchased from a garden center will help determine soil acidity. More detailed soil analyses to determine fertilizer requirements also are helpful. A list of soil testing laboratories is available at your local Extension office. It is important that plants be adequately, yet not excessively, fertilized. (See story on fertilizing.) Improper fertilization will make plants too weak or too vigorous and more subject to disease. There are several other factors to consider as you plan your garden. To prevent the buildup of disease organisms, rotate your crops from year to year on a 4-year rotation. This also will prevent soils from becoming depleted of nutrients by plants that are heavy feeders. Consider the following rotation: root crop, followed by leaf or seed crop, then cabbage family crop, and finally legume. Legume crops, such as peas, help to restore the nitrogen supply in the soil. Select your seeds and plants carefully. In recent years, plant breeders have bred resistance to many diseases into seeds. Check seed catalogs and packages for resistance information. In addition, plant only disease-free transplants. Bargain plants that are unhealthy are no bargain since they may bring diseases to your garden and infect healthy plants. Once your garden is growing, thin plants to provide good air circulation. High humidity and wet leaves favor disease organisms such as mildew and Botrytis blight. In addition, overcrowded plants will be weak and starved for light, nutrients, and water, and will not yield an abundant harvest. Proper watering is critical to maintaining the health and vigor of plants. (See story on watering.) Scratch below the soil surface on a regular basis to check moisture content. Irrigate before the subsurface soil dries. To reduce the chance of leaf disease, water in the morning so that foliage has a chance to dry before nightfall. Control insect pests in and around your garden. (See story on insect pests.) Insects such as aphids and leafhoppers weaken plants and also can carry viruses from infected to non-infected plants. Destroy diseased plants or plant parts as soon as you see them so the disease will not spread. Avoid composting diseased plants; some diseases can live in compost. Weeds not only compete with desired plants for nutrients and water but serve as a reservoir for insects and diseases. It is best to destroy young weeds before they become established. Avoid using herbicides in and around vegetable gardens. Remove weeds with a hoe or by hand-pulling and prevent reestablishment by using a mulch. (See story on weeds.) By practicing these basic gardening principles, you can maintain the health and vigor of your garden and grow vegetables that you will be proud to serve to friends and family.

Produced and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Extension work is a cooperative program of Oregon State University, the U.S. Department of Agriculture, and Oregon counties. Oregon State University Extension Service offers educational programs, activities, and materials without discrimination based on age, color, disability, gender identity or expression, marital status, national origin, race, religion, sex, sexual orientation, or veteran's status. Oregon State University Extension Service is an Equal Opportunity Employer. Copyright © 1995- Oregon State University. Disclaimer.