Garden almanac, Garden Pests

This Week in the Garden (Aug. 21)

This week in the garden is the squash vine borer showing up. A black and orange moth lays its reddish eggs on the undersides of the leaves. The larvae hatch and burrow into the stems (usually where the stem comes out from the ground to around 1 foot up the stem) causing the whole stem to die. You can usually see the hole and some debris. Sometimes you can remove the worm with a vertical slit made into the stem. The use of silver plastic mulch is used to prevent this, confusing the moths. Using Malathion as a drench along the lower foot of the stem in the soil may help. The borers do not attack cucumbers or melons.

Squash borer damage
Squash vine borer damage
Picture of the adult squash borer moth.
Squash borer moth

If late blight is showing up on the tomatoes on the lower leaves, start by removing the dead tomato leaves and use a garden fungicide to prevent infestation on the newer leaves. Leaves will eventually die on determinate tomatoes like Celebrity as the plants mature, this is natural. Determinate varieties bear all at once and the plants are much shorter.

Late blight starting to develop on tomato leaves.
Late blight fungus starts to develop on a tomato leaf.

Some people see a lot of ants on flowers and shrubs. The ants cause no problem. They are following the aphids (which are a problem this year) and herd them like cattle collecting the honeydew the aphids secrete. Honeydew is that sticky substance that gets on your fingers and car sitting under the tree.

Ants taking care of their aphids.
Ants taking care of their aphid herd.

Do not be surprised if your apples and other fruits are ripening early this year. We have had more degree days (days when the temperature is above 80) than usual.

Keep watering newly planted trees. They usually need a couple of gallons twice a week to apply to their roots. Even bigger trees will need additional water especially if they are showing burnt leaves. Keep watering up to soil freeze, especially evergreens. Maples and honey locusts will also benefit from this since having thinner bark, they will desiccate in the winter.

If your beans and cucumbers are soft and little, give more water. Melons and cucumbers are mainly made up of water.

Do not spray weeds in the lawn or use a weed and feed until it gets cooler. The state extension service recommends waiting until the end of September through October.

Garden almanac

This Week in the Garden for Aug 15th

Shippy Realty & Auction Blog potato beetle and larvae on potato leaf

This week in the garden the Colorado potato beetle showed up. These are reddish-orange fleshy larvae turning into the striped beetle adult. It does not take them long to decimate a potato plant. They are later this year so if your plants are maturing just pick them off. If you have a lot of plants that are still green, use Sevin insecticide.

Shippy Realty & Auction Blog fall webworms on an apple tree

Fall webworms are also showing up with their webs in fruit trees and cottonwoods. If you can reach them just pull out the web with the clump of caterpillars. They do not cause much damage this time of year compared to the tent caterpillars in the spring. A female moth lays her eggs and when they hatch, the worms spins this web to protect them from the elements and predators. You do want to control these insects on younger trees before they defoliate the leaves.

Shippy Realty & Auction Blog tomato skin crackling due to increase moisture.

Tomato skin splitting is a problem, however, there is not much you can you to prevent this. When the tomato gets ripe, its skin is no longer elastic. Then we get rain and the skin splits when the insides swell. Some varieties are more susceptible to this condition like cherry tomatoes. A mulch of straw or hay helps.

I had a question about how to tell if the apple is ripe. Lift up at the base of the fruit and if it breaks at the stem, it is ripe.

It is also the time to plant a newly seeded lawn or overseed an existing one because it is cooler than late spring requiring less constant moisture and weed stress is reduced. If you buy a bag of grass seed, it should have a tag on it stating the percentage of grass types and the amount of inert or other materials. The most common is a white tag, however, if it has a blue tag, that means it is certified by testing which is better.

Shippy Realty & Auction Blog pods on a honey locust tree

This is a great time to plant a tree or shrub up to 6 weeks before the soil freezes. The late summer or early fall is cooler, requiring less water and less stress for the tree. If you want a hardy tree, try honey locust. The new varieties do not have the pods. The old honey locust trees with pods planted in the shelterbelts were used as cattle feed in the past. During WWII, the pods were also used for making beer during the rationing.

If you do not mind experimenting and want to try something new in varieties of trees, try growing Turkish filbert, amur cork tree, northern pecan, bald cypress, American sycamore, or yellowwood. Our zone 4 is these trees limit, I have seen them in Pierre, SD. Try at your own risk! They may be easier to grow than our pH-limiting trees like red maple and oaks.

Garden Pests

Powdery Mildew

Last week I mentioned powdery mildew which was on point since quite a few people brought in and sent pictures of this fungus. Let’s go into a little more depth about this topic. The fungus gets into the leaf tissue and sends up fruiting structures which look like talcum powder on the leaves. This disease is plant specific meaning that the powdery mildew on the lilacs does not infect garden vegetables. Powdery mildew on phlox will not spread to other flowers.

Powdery Mildew on lilacs

If you find this talcum-like fungus on trees and shrubs do not worry this late in the season. It will not harm these woody plants except for ever-blooming roses. If it is on cucumbers and they are still in their prime bearing mode or winter and summer squash, I recommend treating these plants.

Powdery Mildew on a squash leaf

Use a garden fungicide like Daconil or a sulfur-based fungicide if you can find it to protect the leaves that are not infected. Sulfur is good because it is volatile and will get underneath the leaves. Some horticultural oils and even a 10% milk solution help coat the leaves protecting them from infection. Even washing the leaves helps reduce the spore amount. For roses and flowers, I would use a garden fungicide this late in the season to protect the unaffected leaves.

Some squash leaves have a natural variation of mottled light green of their leaves. This is natural and not a disease.

Powdery Mildew on a rose bush

Powdery mildew has not been a problem for the last couple of years because it was hotter and dryer. This year is different with the rainfall and cooler night temperatures which is the perfect conditions for spreading the disease.