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So you’re dreaming about your 2020 veggie garden. You examine over scribbles and photos from 2019 and see that you spent tons of time dealing with diseases on your plants. Maybe you even lost some plants or had reduced yields because of disease issues. You consulted with the master gardeners at your local extension office; you treated your plants and beds with organic sprays and amendments, and you removed damaged foliage when you saw it. Did you think at the time that there must be a better way? Did it feel so labor intensive that you wondered how organic farmers do it?

With that in mind, now is the time to set up your strategy for 2020 to better combat those diseases. Like so many things, preparation can leapfrog you to successfully managing diseases in 2020.


Make sure your veggie garden is well-drained and sited with at least 8-10 hours of direct sun. Very few veggies except lettuces will grow well in less sunny locations. Good air circulation is another important factor as is adequate soil fertility and proper pH for your crops. It’s a good idea to apply a general all-purpose amendment like Coast of Maine Castine Blend Organic Raised Bed Mix.   
We have several other organic amendments which you can find HERE that may improve your soil. Doing this as soon as you can work your soil will get your plants off to a good start.



Unfortunately, most diseases winter over so crop rotation is especially important. Keep in mind that many disease-causing organisms attack related plants in the same family. Unrelated plants do not serve as hosts on which these organisms can multiply. For example, avoid planting cabbage, broccoli, radish, or turnips in the same location for two successive years. Beans, a vine crop such as cucumber, or sweet corn could follow cabbage. If the garden has produced vegetables for several years, rotating will reduce the risk of disease-causing organisms that have survived from previous seasons.



Using well-adapted, disease-resistant varieties is the simplest and most efficient method of controlling many diseases. You can find info on disease-resistant varieties at this Cornell Vegetable MD site amidst lots of other useful information. Seed vendors also provide info on disease resistant options for you.

If you start with disease-free seeds, plants, and planting materials (like tomato cages) from reputable vendors, you will be ahead of any issues. This will prevent the unintended introduction of disease to your garden. All planting material needs to be healthy and free of yellowing and brown or black spots and should not be stunted or show poor development. For potatoes, use only certified disease-free tubers or sweet potato slips. Examine transplants thoroughly for signs of leaf or stem disease. Diseased transplants can leave you with long-term issues you don’t need.


Consider your cultural practices. I am talking about controlling weeds, planting at the right time, planting at the proper depth and spacing, using cages or stakes, and watering early in the day to allow rapid drying of foliage. Deny foliar pathogens the moist environment they love. Why weed control? It might surprise you to learn that viruses overwinter in these plants so banish them. Plus, they steal moisture, soil fertility, and possibly even light. Working on wet days is another way to spread diseases that live in water droplets. Resist the urge to work or harvest on those days, unless you want to be the one doing the damage.

The sad truth, however, is that no matter what you do, diseases will creep into your garden. It’s a matter of degree. The better your cultural practices, the less likely you are to have big time disease issues. Many diseases like powdery mildew are wind borne. If your neighbor has it, it’s likely you will too, especially if your garden is part of a community allotment. So, you need to be prepared for them when they arrive.


Lay in a supply of Bacillus subtilis your local garden center. It’s an organic spore-forming bacterium that colonizes plant roots and attacks soil-borne pathogens directly. It also stimulates plants to activate their natural resistance, which can act to control foliar pathogens. With some crops, you can spray preventively. Read the product label for specific use instructions.

A second tool in your arsenal is neem oil at 70%. Neem products are derived from the neem tree, Azadiracta indica. Known as “clarified hydrophobic extract of neem oil”, it needs to be formulated at 70% to be effective. It is an organic treatment for certain diseases under specific conditions. There are lots of product options at your local garden center. Read the product label for specific use instructions.

I would be remiss if I didn’t tell you about Streptomyces lydicus. It’s a beneficial, naturally occurring bacterium that is commonly found in soil. Products that contain S. lydicus can help to control some soil-borne and foliar diseases and are often organically approved. Using S. lydicus as a soil drench can promote healthy root development and improve overall plant strength in addition to combating soil pathogens as the spores germinate and colonize the root zone. Streptomyces lydicus can also be used as a foliar spray. It’s expensive and short-lived so only get and mix what you need for immediate use. Read the product label for specific use instructions.

The last organic fungicide you should know about is Bacillus amyloliquefaciens strain D747. What a mouthful! The label states this disease control product is an approved biofungicide and bactericide for all kinds of plants, including veggies. We can use it either as a foliar spray or soil drench right up to the day of harvest. As a relatively new entry in the home gardener market you may have trouble finding it, so start at your local garden center.


There are proponents of do-it-yourself recipes for garden diseases. I would caution against that for several reasons.

  • First, in a veggie garden you are dealing with food. Wouldn’t you rather be safe with organically approved treatments?
  • Second, with home remedies, there is an issue with the variability of the mix. Online recipes call for a variety of measurements: which one is right?
  • Third, you need to think about the environmental risk that home made recipes pose. Many of these recipes may improve the issue at hand, but with what collateral impacts? Are you comfortable with the effects on amphibians, earthworms, bees, etc.?


For the few pennies spread over the course of the entire growing season (and maybe more), your money is better spent sticking with the commercial products that have been rigorously tested and approved.



Remember the rules of the road for fungal diseases:

  • They spread rapidly so you must act as soon as you identify the issue;
  • In most cases you can’t reverse the disease. You can only control it going forward;
  • Know what you are dealing with and when treatment will be most effective. Don’t waste your time and money on something that you can’t treat or if you have passed the window of opportunity.
  • Accept that sometimes it will be best to remove the plant before it can cause further damage. Suck it up and get rid of the troublemaker.


A single fungicide will not control all fungal diseases so you need to know which one works on what. Your local cooperative extension office can be your best friend in helping you diagnose and treat your garden.

The last thing I want you to remember is to avail yourself of the deep treasure trove of information that Cornell has amassed. They make it freely available to the gardening public at the Cornell Vegetable MD site mentioned earlier.

Written by Lorraine Ballato, author of Success With Hydrangeas: A Gardener’s Guide


Comments (2)

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    • Karol Layman

    • May 14, 2020

    I have mulched my perennial gardens with Fund mulch with kelp. It isn’t the black color that I like. What could I add on top of the mulch for that rich black look?

      • comadmin

      • May 15, 2020

      Hi Karol, if you would like your mulch to be darker, there are mulch colorant concentrates that you can spray it on. We do not sell them, but I’m sure you could find them online.

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