By Jennifer Fairfield, owner The Garden Mill
(Publisher’s note: This column will run in three parts.)
The weather in July certainly made gardening challenging. I don’t know what I liked the least – the heat, the humidity, the rain, or the mosquitoes. I’m glad things seem to be settling down a bit, at least for a little while, anyway. It makes it easier to get things done in my gardens – and there’s lots to do.
In the vegetable garden:
Last month, I gave lots of information about insect pests in the garden, so I thought I’d continue that theme this month, but with diseases, since there are lots of them out there right now.
With all the rain we’ve been getting, plus all the humidity when it’s not raining, diseases are really causing lots of issues in vegetable gardens right now. Below are some of the more common problems people seem to be facing, along with information on what to do about them.
Keep in mind – it’s a lot easier to prevent diseases than to cure them once they have gotten going, so regular applications of fungicide are important.
Blossom End Rot is a very common problem for tomatoes, squash, eggplant, melons, and peppers when we are getting as much rain as we have seen this summer. It also happens when plants aren’t getting enough water.
As I mentioned last month, the problem is a lack of calcium that is generally because the plants aren’t able to take up the calcium in the soil, not necessarily because of a calcium deficiency in the soil itself. It’s best to check your soil for calcium levels before you do anything to add calcium. Adding calcium to soil that already has sufficient levels won’t help your plants.
You can get a soil test that will help you determine the levels of lots of different minerals (including calcium) from MSU Extension Service. Fungicides and pesticides will do nothing to solve blossom end rot. If your soil has sufficient calcium, then ensuring consistent moisture levels in your soil is the best way to prevent this problem. That can be tricky when we’re getting torrential downpours like the one we saw last weekend, and really only well-drained soil can help in that situation.
One other thing to mention on this topic: something that looks like blossom end rot can be caused by a lack of pollination, especially in cucurbits. I suspect that is the cause of the problem I’ve been having with my zucchini this year (pictured here).
My raised bed gardens are very well drained, so I don’t think the problem with my zucchini is related to watering. One key indicator that it is probably a pollination issue, and not a watering/calcium issue, is that it’s happening when the fruit is very small. Zucchini (as well as other cucurbits) needs the bees (or the gardener) to pollinate the flowers on the fruit – without that, zucchini fruit will wither and die, starting at the flower end, when the fruit is still very small. Pollination issues show up when the fruit is small.
If it’s fully formed, and then shows these symptoms, it’s blossom end rot, not poor pollination.
Bacterial Speck on tomatoes shows up as small black spots on leaves (⅛ to ¼ inch in diameter) that are usually more prominent on the undersides of leaves. As the spots age, a yellow halo often develops around the edge. Symptoms can also appear on the fruit as small, black spots.
Copper-based treatments can help to slow the problem down, but there is no cure. If it’s late enough in the season, you can simply let the plants continue to grow, and hope to salvage any unblemished fruits. Do not eat fruits that show signs of the disease. The most effective way to prevent bacterial diseases is to start a regular schedule of spraying your plants with a fungicide, beginning as soon as you plant them.
Bacterial Spot on tomatoes can show on any part of the plant (leaves, stems, fruit), and can lead to plant death.
It is very difficult to tell the difference between bacterial speck and bacterial spot, but if left in the garden, bacterial spot can infect all tomato plants, and ruin your entire crop. Prevention is key – avoid overhead watering, use preventive sprays from the time you plant, don’t work with your plants when their leaves are wet, and always clean your tools with a 10% bleach solution or rubbing alcohol after every cut. Unfortunately, warm, wet weather (such as what we experienced all last month) is the perfect environment for this disease.
(Publisher’s note: additional vegetable information will publish tomorrow.)
