Today we’ll go into a few problems that you may or may not be seeing in your vegetable garden. I’m dividing the topics into two categories: Biotic and Abiotic. Biotic problems mean those issues that arise due to a biological, or living agent, whether it be insect, disease, or human! Abiotic are those that are outside of the above category, so can be physiological, environmental, or cultural in origin. Sometimes the line can be a little less than distinct between the two as we’ll see in several examples. Let’s get sleuthing.
Biotic:Powdery Mildew – this can show up on many vegetable garden plants including squash, cucumber, beans, even peas and carrots can be susceptible although at least here in Colorado we don’t see a lot of that. Typically, powdery mildew begins to make an appearance mid to late in the growing season. It is especially prevalent in gardens that are planted closely, and those that are watered with overhead sprinklers. Planting with adequate spacing and watering the soil not the plant are two great ways to prevent the onset of the disease. Powdery mildew is a fungus which grows thin layers of mycelium along the surface of the leaf or fruit (although growth on fruit is less common.)
David B. Langston, University of Georgia, Bugwood.org
Be aware that some varieties of squash or zucchini have patterns on them that may look similar to powdery mildew. If you aren’t sure, you can send a picture to your local Extension office or you can look for patterns vs. a more random distribution. Patterns are likely natural, more random is more likely to be powdery mildew.
If your garden succumbs to powdery mildew every year in your cucurbits, your melons, squash, cucumbers etc. there are a few different management options. You can trellis your vine crops and grow them vertically; this improves air flow and reduces ambient humidity. You can also remove the oldest leaves as the plant grows, leaving 5-7 of the youngest leaves at any time. Finally, if summer squash is the disease-ridden culprit in your landscape, you can succession plant, plant new squash about a month after your first crop, rogue the first set out once powdery mildew begins to establish.Early Blight in tomato and potato
Paul Bachi, University of Kentucky Research
and Education Center, Bugwood.org
William M. Brown Jr., Bugwood.org
Tomato spotted wilt virus – Another of the diseases that can impact tomatoes, tomato spotted wilt virus is another common disease seen in home gardens. This disease can be transmitted by an insect called a thrip, when it feeds on the tomato it can infest the plant with the TSW virus. Leaves may develop a cupped appearance, with the bottoms becoming bronze and then dying (leaving brown or black tissue). Most typically it can be seen on fruit with concentric rings developing across the fruit. Fruit is fine to eat but may have a poor flavor. It is best to purchase resistant varieties if you’ve had issues in the past. Pull and dispose of the infected plant.
Brenda Kennedy, University of Kentucky, Bugwood.org
/ distorted growth/poor pollination Gerald Holmes, Strawberry
Center, Cal Poly San Luis Obispo, Bugwood.org
Blossom End Rot – Blossom End Rot occurs in quite a
few plant species including tomatoes, peppers, cucumbers, zucchini, squash etc.
We often begin to see it as plants first
ripen in the early summer and into mid-summer. While it is technically caused
by poor calcium in the fruit, this does not necessarily mean that there is
insufficient calcium in the soil. Crushing up eggshells or adding calcium to
water is not likely to rectify the issue. Rather, it is good to practice good
“cultural care” by this I mean you want to make sure you are watering,
mulching, and fertilizing the plants as they need to be cared for. Erratic
watering and cold soils lead to most blossom end rot issues, so look to your
hose and your temperatures before amending with nutrients that are likely not lacking.
Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org
A good way to ensure distorted growth does not occur is to encourage pollinators throughout your garden. Avoid spraying insecticides unless necessary and grow flowers throughout your space to feed your pollinator friends.
Possible herbicide damage on homeowner tomato
Dr. Joey Williamson, Clemson University.
As always, check with your local Extension Office to get more information on this, or any other garden issue. Happy Gardening!