Maryland Grows

Last year, I accidentally introduced bacterial leaf spot into the pepper beds in my own community garden plot and the Derwood Demo Garden, probably through infected seed. BLS is a common disease of peppers that spreads quickly in warm, humid weather (a.k.a. our summers) and can be devastating to an entire crop, especially in small gardens. Lesions on leaves expand until the foliage drops; lesions on fruits make them unattractive though still edible. Cooler, drier weather (the kind we mostly don’t get) can slow or even stop the disease, but otherwise, the only solution once it really gets going is to pull the plants. Trash them, don’t compost them, because while the disease doesn’t linger long in soil, it can last quite a while in plant debris. This also means that garden cleanup is important. Read more about BLS and how to prevent and manage it here.

For this year’s crop, I decided to start disease-resistant varieties of peppers and plant mostly those. That “mostly” ended up being a problem, but I wanted to grow some mildly spicy Anaheims and my favorite heart-shaped sweet ‘Lesya,’ neither of which are resistant to BLS.

In the demo garden, this wasn’t an issue. In fact, I’m growing several other kinds of peppers that aren’t resistant, and all the plants look fantastic and are producing beautifully. We are lucky enough at Derwood to have a nice big garden with plenty of opportunity for crop rotation. The two pepper beds are located far enough away from last year’s diseased beds that even if we left behind some crop residue that nurtured the disease, it would not be able to spread. BLS doesn’t blow on the wind like fungal diseases can; it mostly spreads through contact, including water splashing or gardener’s hands and tools. The DDG plants are safe and we have a great crop to look forward to for a couple more months at least.

My own garden plot, however, is suffering. I put the peppers in a different bed than last year, but the whole plot is only 400 square feet, so I can’t move anything very far away. Some soil that may contain some plant residue may have ended up in the new bed. In any case, the plants definitely have BLS. I’ve already removed several and will have to sacrifice the rest fairly soon. Next year, I will not grow peppers in that plot at all—but luckily I have a new garden at home to host them!

Here are the resistant varieties I grew this year, with some notes from my own garden (again, everything at Derwood is just fine). BLS comes in different races and plants need to have resistance to the particular race to grow successfully under disease pressure. I don’t know which race I have, so I went for the widest possible resistance. BLS resistance has been bred into lots of bell peppers, a few other sweet peppers, several jalapeños, and practically no other types.

(IR=intermediate resistance; HR=high resistance)

• ‘Katana’ shishito. IR to races 0-3, 7, 8. I start with this one because I was thrilled to see it available (I love shishitos, and most are not resistant), but it turned out to be far too susceptible to BLS and has already been pulled. This may be the intermediate resistance operating rather than the race specificity, since several other peppers lack resistance to all races but are doing better with high resistant status.
• ‘Pantera’ jalapeño. HR 1-3, 7, 8. Still hanging in there pretty well but showing early signs of BLS.
• ‘Jalafuego’ jalapeño. HR 1-3, 7, 8. I’m not growing this in my own garden, but we’ve grown it at Derwood for years and have it alongside ‘Pantera’ this year. Last year it did succumb to BLS, but only when the entire bed went. It is more productive than ‘Pantera,’ at least to date.
• ‘Sailfish’ red bell. IR 1-10. Fruits are only ripening now, and unfortunately are showing definite signs of BLS, although the leaves are less affected.
• ‘Nitro’ red bell. IR 1-10. Very early signs of BLS. Fruits only starting to ripen.
• ‘SVPS0953’ snack-size sweet. IR 1-10. Not growing this in my own garden where I suspect it would be succumbing; doing very well at Derwood with several ripe fruits already. Comes in red and yellow as well; this one is orange.
• ‘Goddess’ sweet banana. HR 1-3, 7, 8. This one is still chugging along in my garden and producing like crazy. Very early signs of BLS but I’m hoping the weather change coming this week will delay the disease.

The non-resistant peppers in my plot are also doing poorly, although the Anaheim (‘College 64’) is only mildly affected. I will probably pull everything except maybe the sweet banana in the next week or so (though I want to see if upcoming lower, drier temperatures have any effect on the least-affected plants).

Here are the takeaways:

• Where you’ve removed BLS-affected plants, do a thorough cleanup of plant residue. Also make sure that weeds in the same family (such as nightshades) don’t grow in that area, because they can also harbor the disease. (I don’t think this was my problem, but it’s worth noting.)
• Don’t plan to use the same beds or any close by for the next couple of years.
• If you must grow peppers in the same general area, make sure they are only highly resistant varieties.
• Pull anything that shows symptoms right away. Try not to wait until you get those fruits you’ve been waiting for. (I am so guilty of this.)
• You are allowed to swear at the weather but there really isn’t anything else to do about it short-term. This has been a particularly awful summer for all sorts of plant diseases. We are going to have more summers like this, so identify diseases, research resistant varieties, and give your plants plenty of space and care.

Next year I will have beautiful peppers in my home garden. But if I see the slightest hint of BLS, I won’t delay getting rid of the plants. The following year I’ll test a resistant variety or two in the community garden. We’ll see what happens.

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