Question
QUESTION: Another dogwood question James please. This time it is about a very old native dogwood. Every year the blooms are spectacular on this tree weighted down with blossoms as though it is covered in snow, the talk of the neighborhood! But this year no blossoms at all! It leafed out early and I have noticed lots of little branches growing on the older branches, it looks healthy but whats the matter with it?

ANSWER: Hi Patty,

Before I give you my thoughts can you provide me with a little more detail and history (as far as you know) concerning the tree.

First, where on your property is the tree located? Does it receive full sun, partial sun or full shade? Is it growing in a lawn or in a mulched bed?

Do you notice any other things odd about the tree besides the shoots sprouting from old branches (i.e. deadwood, flaking bark, or mechanical damage of any kind)?

The more details I have about the tree the easier it is for me to accurately identify the culprit.

Thanks

James


---------- FOLLOW-UP ----------

QUESTION: I am not sure how old the dogwood is, we have lived in this house for 18 years and when we moved in it was almost lost behind other trees which we had cut down. After removal of the other trees it is now in full sun and it came on remarkably well. We watched it grow in height and girth to be a very large tree. It is on a slight slope just surrounded by mainly leaf mulch which we rake up each spring and renew with fresh ground up leaves. it is in a more or less natural area near the bottom of the garden.  A few years ago a large pine tree close by was struck by lightening, splitting it from top to bottom, and we think a side flash hit the dogwood, some of the leaves on branches were burnt, but after they were removed the dogwood seemed OK.  Last year I noticed a large area of bark had come off the trunk and it seemed to be oozing. It looked like a large pink sore. I asked the Extension Office about it (I sent a photo) but they said it was normal with old dogwoods and not to worry about it.  That is about it.  I think I may have the photo somewhere if you want to see it.  We live on a mountain and this was all a natural area before they started building houses in 1986. This old dogwood was here before the houses so we try to maintain its natural habitat as much as possible. Thank you James for taking the time and trouble to answer my query. I contacted an arborist to come out and look at it, he charges $125 just to look, then there is whatever treatment they prescribe on top so we were figuring on a $500 bill in the end.  If we could do something ourselves with your help it would be greatly appreciated.  Thanks.

Answer
Thanks for the background information that helps a lot.

There抯 likely a couple different things going on one is a natural phenomenon and the other is brought about by stress.  First I抣l address the lack of flowering.

What抯 likely going on here is a problem that horticulturists have been dealing with for ages. The term used for describing trees that produce abundant flowers/fruit one year (or multiple years in a row) and then little or nothing is 揂lternate Bearing? Trees such as Apples are alternate bearing and horticulturists found that if you don抰 thin out the fruit you can end up with a bumper crop one year followed by a measly crop the next. The reason for this is that there抯 a struggle going on within the plant for vital nutrients necessary for flowing and fruit production. Dogwoods, like many other trees and shrubs, set flower buds for next year at the end of the growing season. So, in your case, if you had a particularly abundant flowering/fruiting during last season then the tree was left with very little nutrients left to set this year抯 flower buds. What your tree is doing is essentially resting. It will use this year to rebuild all the necessary compounds for flowering/fruiting next season. At the end of this season you should see plenty of round buds at the terminal end of the shoots indicating the tree ready to again flower next year.

The condition described above is also compounded by the fact that lightning stuck the adjacent tree and the wounding on the trunk you observed. A common response that many trees have to stress is to produce 揺picormic shoots?or 搒uckers?as they抮e commonly referred to as. The reason trees do this is because they need to rebuild damaged tissue and compartmentalize wounds.  In order to keep up with the demands for more sugars and carbohydrates for repairs, the tree needs more leaves. So卛t suckers out.

My recommendation in this case is that you allow the suckers to grow at least for this season so the tree can rest and recover. I抦 also concerned that the tree is vulnerable to attack from dogwood borer. This insect takes advantage of open wounds to lay eggs which develop into very destructive larvae (Link below to more information). You most likely can buy the required insecticide and means of application from Lowes or Home Depot. I抦 not sure what name it will go under but if you read the labels they will contain one of two active ingredients, Permethrin or Bifenthrin. These chemicals are applied as a trunk spray to kill emerging adults and prevent them from laying new eggs. It does NOT kill any larvae already in the tree.

A more environmentally friendly option is to use entomopathogenic nematodes that are also applied to the trunk. Dealing with nematodes can be tricky and you must remember that you抮e dealing with a living organism that must be handled with care. You can buy them online or at some garden centers.

Follow the instructions exactly whenever you抮e dealing with pesticides or biological controls. When it comes to pesticides; the label is the law.

I hope this gives you some things to think about and hopefully you抣l be able to take care of this tree without breaking the bank.  

Best of luck to you and the tree!

James

Dogwood Borer Info:
http://entnemdept.ufl.edu/creatures/trees/moths/dogwood_borer.htm