Preventing Vegetable Diseases in the Garden

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Check lists can be useful to be sure projects and tasks get done in a timely fashion. Going down a check list for the garden to lessen disease is just another part of planning what you are going to grow this season. My check list covers 8 points. Not all will apply to every garden and some gardens may need to cover more.


  • Grow disease resistant varieties - one of the easiest ways to manage vegetable plant diseases. These are most often listed in the seed catalogs and noted on the seed packets as F1 hybrids. Any variety that has a series of initials behind the name denotes disease resistance, the more initials, the more resistance.
  • Choose the best site possible – vegetables prefer sun all day long. With less than full sun, leafy greens and early root crops will perform well. Vegetables that produce fruits will be delayed and have lower productivity. 6-8 hours is the minimum to expect good yields.
  • Water properly – even consistent soil moisture is important for sustained high quality yields. Critical times for water for Tomatoes, cucumbers and Peppers for example are anytime during fruit development. Bulb onions may be limited in size if water is lacking at any point of bulb expansion. Water the soil and not the plants. Leaving plant foliage wet at night just about ensures the right environment for disease development.
  • Garden sanitation – this is done before planting, during the growing season as well as at the end. A good clean garden bed ensures that diseased plant parts are not present. Removing fruits or vegetable plant parts that are diseased limits further spread and fall clean up removes the majority of the disease inoculum for the following year. Sanitation also includes the weeds around the garden and nearby. More on that just below.
  • Manage insect populations -Vegetable diseases that are spread by insects like aphids will feed on nearby weeds that will host the disease without showing any symptoms and then feed on our vegetable plants, spreading the disease. More of a concern as the growing season progresses than first thing at planting time.
  • Promote good growth – Healthy plants resist diseases better and provide greater yields. Use a starter fertilizer to stimulate roots and later consider a side dress of fertilizer as the vegetables start to flower and produce fruits. This along with the even watering will produce the best sized and uniform yields.
  • Follow crop rotations – this is difficult to do in the smaller home gardens as space is limited and why using F1 hybrids are so important. Large to very large gardens can benefit more. Rotating plant families between the solanaceous crops (Tomato, pepper potato and eggplant) with cucurbits (cucumber, squash, melon and pumpkin) with Cole crops (cabbage, kale, broccoli, and others). A three year rotation greatly reduces soil disease populations.
  • Fungicides – Sometimes weather conditions can go against all the good things we do to prevent vegetables diseases. When a disease is identified and caught early, fungicide applications can really help. Fungicides are only preventative and very through coverage is critical for good control.

About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.