After heat comes pests and problems

A lady beetle works on a crape myrtle that is showing signs of an aphid infestation

 (honeydew on the leaves, especially). (Photos: Kathy Morrison)

Record string of hot days may be finally over

By Debbie Arrington

The final numbers are not yet in, but 2020 will have another distinction: It ranks among the warmest years on record in Sacramento.

According to weather experts, Sacramento hit 90 degrees or hotter on 125 days in 2020 – including Tuesday. In all of 2019, Sacramento had 93 days at 90 or hotter. That’s like a month extra of over-90 days!

Historically, those 125 days eclipsed by more than two weeks the previous record of 90-plus hot days – 110, set in 1984.

Fortunately, our weather is finally cooling down to something approaching normal for late October in Sacramento. In fact, it may even feel chilly. The National Weather Service forecasts a high of 67 degrees on Sunday with days in the low 70s most of next week.

What does this mean in your garden? An onslaught of pest and fungal issues.

* After so much heat and dusty dry conditions, spider mites have been loving our Indian summer. They’ll continue to stick around until rain or a strong blast from the hose knocks them off plants.

Aphid damage is apparent on this narrow-leaf milkweed plant.
Knock aphids off with water.

* Aphids and white flies are having a big surge. They’re attacking new tender growth on plants that are having a late growth spurt. Try knocking them off with water, too, or some insecticidal soap.

* Late-season caterpillars are munching holes in anything edible. Look on the underside of leaves and pick them off.

* Snails and slugs also like cooler weather – and eat everything. Pick them off when they’re most active (about an hour after nightfall).

* Expect to see an explosion of powdery mildew on roses and other susceptible shrubs. This fungal disease lurks in old mulch or fallen leaves under bushes. When high temperatures cool into the 70s (as we’ll see this week), powdery mildew suddenly returns. If leaves look puckered (but not yet dusted with white), pick them off; that puckering precedes the spores.

* Rust, another fungal disease, returns in late October with a vengeance. Again, it’s the weather. Rust spores look like orange specks on the underside of rose leaves. By removing infected leaves early, you can stop a major outbreak. Pick up fallen foliage to prevent rust from returning next spring.