Plant Disease Prevention in the Vegetable Garden

August 19, 2009

Blights, wilts, and viruses, are just a few of the terms that many backyard gardeners have received a rude and unwanted introduction to this growing season. Bob Guillow publishes the site at Garden Manuals and stops by today to share the following information about plant diseases and tips for reducing their impact in your vegetable garden:

Diseased-Tomato-PlantAlthough diseases can appear despite your best efforts, if you’re familiar with their symptoms and the controls that can be used against them, you’ll have a better chance of stopping them before they can become a problem.

Sensible Cultural Practices to Keep Plant Diseases at Bay

While good gardening practices will fend off many diseases, you can’t always prevent a disease from attacking a prized plant. To help keep plant problems under control, try taking the following steps:

  • Transplant Carefully – This minimizes root damage. When broken, roots are susceptible to certain soil born diseases.
  • Keep Plants Healthy – Give them the water, light and fertilizer they need to flourish.
  • Keep the Garden Clean – Do a thorough fall cleanup each year utilizing your favorite garden tools. Remove weeds, since pathogens may over-winter on them. Strip off any diseased leaves remaining on plants and rake up and discard all diseased leaves on the ground. You may also want to rake up other garden debris, though, if not diseased, it can serve as good mulch.
  • Buy Disease-Resistant Plants – Vegetable seed packets are labeled to indicate the particular plant’s disease resistance. Plant tags on fruit trees or ornamental trees and shrubs also contain this information.
  • Take Care Not To Injure Plants – An open wound on a plant stem or tree trunk readily admits bacteria and fungi.
  • Avoid Wet Weather Garden Work – You may unwittingly spread water-borne pathogens as you move about from one spot to the next.
  • Remove Diseased Plants – If certain plants are constantly afflicted by disease, eliminate them from the garden and replace them with less troublesome choices. This solution is simpler than trying to control the disease, and it removes the source of further infection.
  • Install a Drip Irrigation System – Minimize the splashing water that can spread water-borne pathogens.

Unfriendly Sources of Backyard Garden Diseases

Fungi, bacteria and viruses are the pathogens most often responsible for plant diseases. Unlike green plants, these organisms are incapable of manufacturing their own food and must instead take it from a host plant. Fungi can live in the soil, but the bacteria and viruses that cause plant problems cannot survive outside of their host.

Fungi multiply by tiny reproductive bodies called spores, which they produce in great quantity. Spores of some fungi enter plants through the roots; others land on leaves, where they attach and complete their life cycle.

Simple Organisms Create Complex Problems

Bacteria need water and warmth to multiply, so the diseases they cause tend to be more prevalent in warm, wet climates. These single-celled organisms enter plants through wounds and cuts.

Viruses are even smaller than bacteria; they can reproduce only within the actual cells of the host organism. Some viruses are transmitted by insects such as aphids, leafhoppers and thrips; others are carried by infected seeds and pollen. Viruses also enter plants through wounds and cuts.

Tomorrow Bob will return to describe the most widespread backyard plant diseases and share some organic practices to help keep them in check.

Bob Guillow has been a content writer for over 10 years. His expertise ranges from gardening to IT. His website, is the culmination of six years of gardening experience.

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  • reba

    what makes brown spots on green bean leaves

  • i have a pumpkin plant and it has a few pumpkins already growing..can i pinch the plant to stop it from growing more more so the plant can focus on the few pumpkins growing already??

  • Kenny Point

    Hi Rosie, you can pinch the plant runners but I would probably just remove the extra flowers to keep the plant from setting more fruits.

  • Debbie

    I have planted my very first tomato plants and they are starting to flower but the flower is turning down. Does that mean they have a disease?

  • Kenny Point

    Debbie, I don’t think that that is a sign of disease, I would just watch to ensure that the flowers set fruit and grow into tomatoes.

  • Tanya

    Hi i have tomato plants that I have grown from seed three of them had a disease and I have taken all the tomatoes off and put them on the window seal, I still have four left but I see that there are big brown patches on the stems of a couple of them I have taken all bad leaves off but just need know if I need to do the same with the others, plus my cucumber leaves are going yellow is that natural and do I have to take them off or just leave them.

    Thank you


  • Kim

    What’s eating my pepper plants? The leaves are being eaten, they are not producing any flowers, and there seems to be “metalic eggs” underneath some of the leaves. Any ideas?

  • Susan

    My cucumber plants are flowering and new cucumbers are present, but shortly after the flower dies and it turns brown and kills the baby cucumber with it. We have been having a lot of rain, could it be bacterial? There have been some leaves turning brown as well.

  • Kenny Point

    Hi Susan, another possibility is that it is due to poor pollination. It isn’t uncommon for the early fruits to drop like that but the situation usually improves with later fruits. I would just keep an eye on them and if it is a disease at least there is still time for you to remove the affected cucumber vines and replant.

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