The Yellow Farmhouse Garden

June 3, 2011

Plum Curculio Damage on Apples

Filed under: Fruit,Insects,Trees — bob @ 10:08 am

The cold, wet spring we had is fast becoming a distant memory now that nice weather is finally here. One thing that keeps reminding me of spring is the insect damage I see on my apples.

It was difficult for me to spray the apples at just the right time in between all the rainy days we had early in the season.  As a result, my apples are showing signs of plum curculio damage.

The plum curculio is a small (1/4 inch long) beetle that attacks apples, pears, peaches, cherries and of course, plums.  The adult female emerged a couple of weeks after the apple blossoms fell.  That’s when I should have sprayed. But, it was rainy and I was gone for a few days and missed the critical spray.

The adult female curculio cuts a crescent shaped slit in the skin of the apple, and then lays an egg under the flap of apple skin.  The egg hatches and the tiny worn that emerges starts eating the young apple.

Plum curculio damage on developing apples.

Many of these damaged apples will fall off; some will stay on the tree and grow to full size but will have scars left from the curculio attack. The cherries, peaches and plums won’t be so lucky; they will all fall to the ground carrying the growing curculio larvae with them. There they will grow.  As they reach full size, the burrow into the soil. Later in the summer, the mature curculios emerge from the soil and feed for a while before they hibernate under the leaves for winter.

The plum curculios are still be laying eggs at this point in the season, so it is a good idea to keep up your spraying routine. Other pests will be out in the orchard attacking your fruit trees too.

Bob

August 31, 2010

New Threat to Walnut Trees

Filed under: Disease,Insects,Trees — bob @ 9:08 am

Another potential disease problem is over the horizon threatening our local trees.  This time it is the Black Walnuts that are at risk.

A fungal infection called Thousand Cankers has been killing Black Walnut trees in the western part of the United States for several years.  It has been confined to nine states in the Rocky Mountain area and westward until July of this year. Its range seemed to be associated with a different walnut called the Arizona Walnut.  Black Walnut is not native to that particular area but was brought in and planted by arborists, landscapers and others.

This summer it was confirmed that the disease had spread to at least one location in the Eastern USA,  Knoxville Tennessee.  Scientists now believe that it may have been present there for a number of years without anyone knowing about it.

At this time Thousand Canker disease is NOT present in Michigan.

The disease is caused by a fungus which is carried by a very tiny beetle called The Walnut Twig Beetle.  Despite its name the Twig Beetle  attacks larger branches or even the trunk of Black Walnut Trees by tunneling under the bark. They leave small “galleries” or tunnels in the wood caused by the beetle larvae feeding there.

When the larvae mature into adults they emerge from the branches out of small holes chewed through the bark. The fungus then infects the damaged area and causes a small lesion or “canker”.  These cankers spread very fast and merge together eventually moving from the outer bark into the cambium layer.  Each branch has a tremendous number of cankers which is how the disease got its name.

The cankers themselves are often difficult to see and identify.  A special lab test is needed for positive identification.

There is no cure or control for either the Twig Beetle or Thousand Cankers, plant pathologists are working on that though.

In the meanwhile we can help slow down the spread of this problem by not moving firewood just like we do to prevent Emerald Ash Borer from spreading.

There is no federal quarantine on moving wood products but the State of Michigan has issued its own quarantine against shipping articles made of wood from certain western states.

The USDA Forest Service has a good publication on this problem.

As I mentioned earlier, Thousand Cankers is not present in Michigan at this time. Keep in mind that there are a lot of other things that can cause a tree to show signs of  die-back  other than this disease.

Bob

August 17, 2010

Parasitized Tomato Hornworm

Filed under: Insects,Vegetables — bob @ 12:55 pm

There seems to be an abundance of Hornworms in the garden this year.  A couple of posts ago I discussed picking the pests off of the plants by hand as one way of controlling them.

This morning while picking even more Hornworms off the tomatoes, I came across one that I though you should see. It had been parasitized by a small insect  known as a braconid wasp.

These tiny wasps  fly around the garden looking for likely victims. When they find a suitable host, they sting the caterpillar and lay their eggs inside its body.  The eggs hatch and the larvae feed on the innards the worm.  As the wasp larvae near the pupation stage, they chew through the caterpillar’s skin and spin small white  cocoons made of silk which remain stuck on the surface of their host. The cocoons are sometimes mistaken for eggs by some gardeners.

This Hornworm has 3 or 4 dozen cocoons on its back. Each cocoon contains one wasp that will emerge and begin hunting more caterpillars to parasitize.

Days later the new fully-developed adult wasps will emerge from the cocoons and  fly off to find new caterpillars to parasitize.  Needless to say the caterpillar does not survive the procedure, which is good news for us gardeners.

The adult flying wasp does get hungry but does not eat caterpillars instead it feeds on nectar from flowers

If you find a caterpillar with these cocoons on its body, leave it undisturbed where you found it so that you will have dozens more helpers in the battle against the Tomato Hornworm.

Bob

August 2, 2010

Tomato Hornworms Are Back

Filed under: Insects — bob @ 6:42 pm

The week before last I saw the first few Tomato Hornworms in our garden. I was able to take care of them pretty quickly by picking off the first two or three.

Today they came back with a vengeance.  I found Hornworms all over our tomatoes. Here’s the first batch I “harvested” from the plants:

The first batch of today's Tomato Hornworms.

There are a few alternatives  you can use to get rid of Hornworms these include spraying chemical or biological insecticides, applying  insecticidal dusts or picking them off by hand, the method I prefer.

Whichever method you choose, do it quickly. They can grow from cute tiny caterpillars that hardly make a mark on a leaf to monsters like these  in just a few days. Once they reach this size, they can literally devour an entire plant overnight.

If you decide to use the hand pick method, here’s a tip that will help you find them.  Since Hornworms’ camouflage is so effective, they can be very difficult to detect. Go thorough your plants and pick off the ones you see right away. Then go do something else in another part of your garden for a while, even ten or twenty minutes will do.  This gives your eyes a chance to “re-set”.  When you come back to look for the worms, you can often spot the ones you missed the first time through.

It also helps to check them a couple times throughout the day. As the light changes, you may be able to spot the rest of them that are hiding.

In my first time through my plants I found this batch of worms.  After about a half an hour, I found eight more in the same spots I looked at the first time around!

You may be wondering what I was going to do with a bowl full of Tomato Hornworms. I took them over to our chickens and tossed the worms  in one at a time. This provides loads of entertainment for both the chickens and myself.  The chickens like to play several games with the worms like “Chicken Football” and ” Chicken Rugby” and my favorite “Tug of War”.

To avoid a lot of  disappointment,  check those tomato plants as soon as you can… before you head out to the beach.

Bob

June 23, 2010

Apple Codling Moth

Filed under: Fruit,Insects — bob @ 12:26 pm

Growing good apples is a little tricky because of all of the pests that feed on them and cause damage to the fruit.

We discussed the Curculio a couple of posts ago, this time we need to talk about another major pest on apples, the Codling Moth.  This is the proverbial “worm in the apple” that you see in those old-timey cartoons. It is not a worm as such but rather is the larva of a moth.

The Codling Moth is not a very attractive moth as seen in this photo taken by MSU Horticulturists.

Normally there are two generations of this pest in our area although in some years we see a third generation as well depending upon that season’s weather.

According to scientists who measure certain weather and other conditions, the Codling Moth larvae are hatching from their eggs right now.  After the larvae hatch, they will begin to burrow into the fruit.  Once they get inside the fruit they cannot be killed because  insecticides cannot reach them.

Codling Moth damage on apple. (MSU photo)

Timing is very critical for controlling Codling Moth effectively since the larvae begin to burrow into the fruit just hours after hatching. Large commercial orchards use sophisticated traps to monitor adult moths. With that information they can determine when egg laying happens  and apply their sprays accordingly.  For the rest of us we have to pretty much rely on our 10 day to two week spray schedule to do the trick.

Michigan State University Extension in Van Buren County has a very detailed web page regarding this pest.

Another generation of Codling Moth can be expected in August.

Bob

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