Chestnut Challenges

Chestnut Challenges

Locally here in the Louisville, Kentucky area, there have been several insect outbreaks found affecting American chestnut plantings this spring.  Photos and samples have been sent to the University of Kentucky for insect verification, but I have indicated with the photos what the culprit appears to be.

Ambrosia Beetle:

 

These small holes are on a lower branch of a 10 year old tree.  The entire branch is dead from 2” diameter on up.  Usually, AB will attack trees when they are at about 1.5” diameter – or similar sized branches in older trees.  Monitoring can be done with AB traps beginning in March.  If the beetles are found, then a spraying regime can begin to protect the trees.

One bad thing about AB is that it will introduce a fungus into the tree that may continue to affect the tree even after beetle outbreaks have been controlled.  Prevention is important for our display trees at area sites.

Round Headed Borer or Long-horned Beetle:

 

Although it is hard to tell from the photo, these holes are much larger than those caused by Ambrosia beetle. The resulting dead trees send up stump sprouts, which can be managed to “replace” the lost tree. Similar to blight, the above-ground portion of the tree has been killed, but the root system remains viable.

In both cases, once the insect identities are confirmed, spraying of tree trunks to the point of runoff will be done on a regular basis with a 2.5% permethrin product.  This will kill larvae not yet in the tree and will kill emerging adults, so as to not spread the attack.

I always say that, “everything likes chestnuts!”  By this, I mean the nuts, the leaves, the twigs, the wood, etc.  This species used to make up about 25% of the forests in the Eastern US.  What a significant impact on wildlife when they basically disappeared due to the introduced blight.

 

Leaf Eating Insects

I have a chestnut tree growing in my front yard, doing quite well during its second year.  It is well over 6 feet tall and there are still a couple of month remaining in the growing season!  The other evening, I noticed some of the leaves were “skelotonized!”  This is a sure sign of Japanese beetles.  Upon closer inspection, I found that there were 2 or 3 dozen beetles on the leaves!  A quick dusting of Sevin dust seems to have resolved the problem, as yesterday I found no beetles on the tree!

Sometimes this time of year, you start to see leaves beginning to curl a bit from the edges.  Many times, this is caused by sucking insects, such as leaf hoppers and aphids.  Sometimes, you must look at both the top of the leaf, as well as the underside, to find what might be affecting your tree.

Keep your trees healthy and they will put on more growth!