Thanks to the University of Maryland/Maryland Grows for this informative article about disease-resistant vegetables.

I mentioned in my post last month that many of the pepper plants I grew from seed this year were infected by bacterial leaf spot. I did my best to remove diseased material from the garden. However, undoubtedly some of it still lingers in the soil and might survive to infect plants next year, so I will plan to grow varieties that are resistant to this disease.

And no, I don’t just have a list of these varieties in my head. I’ll have to do some research. Maybe you’ve faced this problem too. All or some of your tomatoes or squash or some other vegetable succumbed to a disease you managed to get identified—and your friendly Master Gardener or Extension specialist advised you to plant resistant varieties. How do you go about finding them?

First, check out Cornell Cooperative Extension’s Disease Resistant Vegetable Varieties page. Here you can find a list for each of many common vegetables of available varieties and the diseases to which they’re resistant. For example, if you have a problem with fusarium wilt in tomatoes, click on Tomato and then skim down the list to note all the varieties with fusarium wilt resistance. (Lucky you; there are lots.) You can also download the information in spreadsheet form for easy reference.

If you have favorite seed catalogs, they can be another good source. Most seed catalogs will add codes to each variety listing that represent disease resistance. For example, fusarium wilt is coded as “F” and if you see “F1-2” that means it’s resistant to both races 1 and 2 of fusarium. (The more resistance, the better, since you probably don’t know which race infected your plants.) Somewhere in the catalog section for each vegetable there will be a list of codes and what they mean.

If you don’t grow your own plants from seed, use these resources anyway. Make a list of resistant varieties, find a garden center or other plant source with a wide selection, and pick out the plants that meet your criteria. Make sure the plants you select look healthy!

Here are some other things to keep in mind:

• Hybrid varieties are more likely than heirloom or other open-pollinated varieties to have demonstrated disease resistance. If you have anecdotal evidence that an heirloom is pretty resistant, try it out. You might want to grow it separately from your bed of resistant types. Same goes with that variety you just have to grow because you can’t do without it. You might suspect it may come down with the bug—grow it away from the others.
• “Disease resistant” does not mean “can’t possibly get the disease.” If the pathogen is present, it will probably still infect plants. The resistant plants will stay healthy much longer—maybe until the very end of the season, if you’re lucky.
• Know the source of your pathogen: is it present in the soil, or will it reappear blown in on the wind, or is it more likely to come from infected seed or plant material? Knowing a bit about how transmission works will help you strategize to keep plants healthy. The HGIC website is a good source for information about plant diseases and how they spread (hint: look at the entry for the vegetable and it will list relevant diseases).
• There may be other methods available to keep disease away, such as treating seeds with bleach or hot water, using fungicides, and most importantly keeping soil around plants covered with mulch to prevent splashing onto leaves. Also try to avoid overhead watering; water at the base of the plant. You can also remove and destroy infected plant parts when you spot them. Using these methods in combination with planting resistant varieties will increase your odds of success.

Do your research and have a bountiful, disease-free growing season next year!

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

---

In addition, if you are looking to buy or sell your home (with or without a garden), contact Gigi today.