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Archive for July, 2013

Japanese beetles crawl over Buddleia flowers

Just the other day this question was posted on our Discussion Board:

I’m having a problem with my Heliopsis helianthoides ‘Summer Sun’. It appears that the petals are being “cut” off. For example this morning when I looked at the flowers I had two in full bloom. When I looked a few hours later, some petals were missing. Now when I looked at roughly 7:30 pm the one bloom only has one petal left and the other bloom is denuded of petals about 75% of the way around the center. This is not the first day that this has been happening. It’s not that petals are dropping off as there is a remnant of the petal around the center of the flower; it appears as if the petals have been cut off.

Japanese beetles shred a beautiful hibiscus flower.

Japanese beetles shred a hibiscus flower.

Hmmmm – I’ve seen this before with Echinacea (coneflowers), Hibiscus, Chrysanthemum, and many other plants. The culprit is beetles. In our area it’s probably the Japanese beetle that does the most damage to flowers, foliage, and fruit at this time of year. Although bean beetles, Colorado potato beetles, and stinkbugs are right up there in terms of damage to plants, Japanese beetles seem to do the most damage to ornamentals, particularly to the flowers, flower buds, and foliage.

Adult Japanese beetles began emerging from the ground in early July and have since been flying around in search of food and mates. I think they were a bit later than normal this year because we had such a late spring. I haven’t seen very many in my garden – just a few on the Rattlesnake and Kentucky Wonder pole beans. I hope this trend continues!

Japanese beetles devour a mandevilla flower bud

Japanese beetles swarm over and
devour mandevilla flower buds

A few years ago they were really bad and devoured most of our young apples, the corn silk, and the foliage of our pole beans. How very annoying! Perhaps the excess rain this year has contributed to their lower numbers – at least in my gardens. Our 5″ of rain (in one day) may have come right about the time the adults were beginning to emerge from the pupae so a bunch may have drowned. Can’t say I’m sad about that!

There are several different ways to control Japanese beetles in the flower garden and in the vegetable garden. I remember when I was growing up, my grandfather used to have a small bucket of creosote that he would keep in the garden by the Kentucky Wonder beans. Every time we went into the garden we would have to take the bucket and knock the beetles off the beans into the creosote. We now do this with a bucket of soapy water – same results.

There will be nothing left of this Rose-of-Sharon flower when these beetles are through!

Japanese beetles attack and destroy
a Rose-of-Sharon flower

Control with an insecticide is tricky since Japanese beetles are often attacking plants that are blooming; eating the foliage or worse, the flowers that the bees and other pollinators frequent. Our bees have enough trouble these days without being poisoned by the careless spraying of insecticides.

That’s why it is so important to read and follow the label directions whenever you spray any pesticide. There are specific “Precautionary Statements” on the label which include “Environmental Hazards”. You should always read this section before spraying.

Japanese beetles love corn silk. Daren Mueller, Iowa State University, Bugwood.org

Japanese beetles love corn silk.
Daren Mueller, Iowa State University,
Bugwood.org

Bonide has developed an organic insect control called Captain Jack’s Deadbug Brew which is listed for controlling Japanese beetles and many other pests. It can be used in the vegetable garden as well as on ornamentals. Captain Jack’s Deadbug Brew contains spinosad, an insecticide derived from a naturally occurring bacterium. The nice thing about spinosad is that it targets many different plant pests but spares most beneficial insects. It is similar in this way to Bt but it lasts longer in the garden and targets a broader range of insect pests.

The Captain Jack’s label states that the product is toxic to bees if they are exposed to the treated plants during the first 3 hours following application (while the spray is still wet). Once it dries, spinosad is relatively harmless to bees. Because of this, you should spray your plants in the evening when the bees are less active. This will allow plenty of time for the spray to dry before the bees and other pollinators visit the plants that have been treated.

Here’s hoping the beetles stay out of your gardens this summer!

Until next time – Happy Gardening!

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Cedar apple rust on young apples

Well, it’s been quite a year so far.

We have had so much rain that it has been hard to get anything done in the garden. One day in June at our house we got 4¾” of rain from 3 separate “cloudbursts” that occurred within 6 hour period. Our driveway was a river and was washed out in several places. We were very lucky that the vegetable garden didn’t wash away that afternoon but thanks to a berm of juniper branches and the ditch that Eric dug last year, it was mostly spared!

Brown rot has already destroyed many of the peaches.

Brown rot has already destroyed
many of the peaches.

Unfortunately, the orchard isn’t looking very promising this year. Most of our weekends this spring were either rainy or too windy to spray the fruit trees and boy does it show! Last year we had a great crop of apples because I was able to spray All Seasons Oil and copper fungicide as needed.

This year disease is the main problem. The wet, humid weather has really promoted the development and spread of disease in the orchard as well as in the flower gardens and the vegetable garden. Spraying with a fungicide would have helped to some extent but conditions have been so favorable this year that I feel that disease problems were inevitable!

A stinkbug on one of the peaches. Clear, sticky gum on the surface of the peach shows where they were feeding.

A stinkbug on one of the peaches. Clear,
sticky gum on the surface of the peach
shows where they were feeding.

A few weeks ago I was dismayed to see that brown rot had already consumed some of the peaches and others were beginning to show signs of infection. On top of that, stinkbugs were crawling over the peaches causing damage to fruit that was otherwise still healthy! Everywhere they had punctured the skin of the peach, a blob of sticky goo had formed in response to the injury caused by their feeding.

Rats – there goes my peach crop for this year.

The grapes and apples are having their own disease issues with the appearance of black rot on most of the grape clusters and rust on the apples.

The older cucumber leaves were riddled with a fungal disease.

The older cucumber leaves were
riddled with a fungal disease.

In the vegetable garden, my cucumbers began developing spots on the older leaves which I think is anthracnose or possibly downy mildew. I was in panic mode then – everyone is counting on getting some pickles this year!

All of these diseases develop rapidly and spread readily in the moist, humid conditions we’ve been experiencing this season. It seems like we’ve had rain nearly everyday lately!

Many of the fungal diseases in the garden can be reduced by practicing good sanitation during the season and in the fall. I know I say this a lot but it is really important to rake up and remove all dropped leaves, fruits, and cuttings from the garden. This plant debris is full of fungal spores which can infect new growth as the season progresses or reinfect plants when they emerge the following spring. This is especially important in the vegetable garden and in the orchard.

Grape mummies must be removed from the vine to reduce infection next season.

Grape mummies must be removed
from the vine to reduce infection
next season.

This means all those little grape mummies and all the peach and plum mummies must be removed from the trees (or vines) and bagged up. All the ones that have fallen to the ground must be carefully raked up and removed along with all the fallen leaves. In the early spring, prune out any twigs and branches with cankers and thin the trees and grape vines to increase air circulation and reduce humidity around the plants. Quite a job but well worth it in the long run.

What I did with my cucumbers was to remove all the diseased leaves and then spray the plants with Bonide Copper Fungicide. This should help control the spread of the disease to the healthy leaves. That was a two weeks ago and they are still looking good thank goodness!

Diseased lower leaves on my cucumbers.

Diseased lower cucumber leaves.

Cucumbers after diseased leaves were removed.

After removal of diseased leaves.

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To help control disease (and many insect pests), clean up the vegetable garden at the end of the season. Rake up and remove any diseased plant material. If you are able, be sure to rotate your crops the following season.

Another way to reduce disease in the garden is to plant disease resistant varieties whenever possible. There are many new cultivars and hybrids of trees, shrubs, perennials, annuals and vegetables that show resistance to many of the common fungal diseases.

Until next time – Happy Gardening!

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