Author Archives: Brian Eshenaur

June 7, 2013

Allies in the Trees

Do you recognize this one? I saw this insect at a couple of tree farms during the last week of May and first week of June. This is an immature ladybug a.k.a. Ladybird beetle. The ladybug larvae, like the adult beetles they become, are voracious eaters of aphids and other insects.

Ladybug larva. Click on image for larger view.

ladybug pupa

The larva becomes a pupa before morphing into an adult beetle.

ladybug adults

An adult ladybug may consume 5000 insects in its lifespan. The ladybug on the right is on its way to a meal of balsam twig aphids.

ladybug eggs

This is a good sign. Bright yellow ladybug eggs hanging from a fir needle means more of these “eating machines” will be hatching soon.

There are many other beneficial creatures, which feed on pests in tree farms and often go unnoticed.  These include “good” mites, various predatory and parasitic insects, spiders and even birds.  By keeping pesticide applications to a minimum the populations of the beneficial partners are maintained and nature can do its good work without us even knowing it. 

May 21, 2013

Quince Rust on Junipers

Another rust disease in the cedar rust group, quince rust is the most likely to cause serious dieback on junipers.

With this disease the bright orange “galls” are actually just slightly swollen lesions on the stems. Widespread lesions can lead to significant browning of the branch tips as pictured above. Spores which spread from these galls in the spring infect the alternate hosts of quince, hawthorn, crabapple or apple tree leaves. On hawthorn trees this disease causes causes symptoms on the leaves, white fringes on the fruit and swellings and distortion of the branch tips.

As with  similar rust diseases separating the juniper from the alternate host (the further apart the better) can help keep this disease in check.

For lists of resistant varieties and fungicides labeled for managing this disease refer to the Disease Section of  Cornell Guidelines for Commercial Production and Maintenance of Trees and Shrubs.

May 14, 2013

Hawthorn Rust

Bright orange swellings can be seen at this time of year on some Eastern redcedars and other junipers.  After a rain those small, translucent-orange galls with gel-like projections appear.  These weird galls are caused by an intriguing fungus that needs two different host plants to live!

Hawthorn rust galls on Eastern redcedar.
Photo take in May, Onondaga County, NY.

Close up of galls. (Click for expanded view.)
Photo take in May, Monroe County, NY.

In the spring the orange masses expand after a rainfall and release  spores that can travel though the air and only infect the leaves of a hawthorn, apple tree or similar host (see below).  Then in the fall, from spots that formed on the hawthorn or apple leaves, spores are produced that can only infect a juniper/cedar.  The cycle continues in the spring when you can see new galls on the juniper/cedar.  Although a problem for apple growers this rust disease does not cause serious harm to the junipers.   There are other rusts that can cause problems with junipers such as quince rust.

In addition to the foliage of hawthorn and apples this disease can occasionally affect the leaves of affect crabapple, service berry or quince or pear.  However this disease does not affect any other evergreen tree species.  Only  redcedars and junipers can become infected.

 

April 26, 2013

Armillaria Root Rot (Shoestring Rot)

Fraser fir killed by Armillaria

This disease is caused by several species of the fungus Armillaria.  It is also known as shoestring rot due to the dark wiry strands it produces.  These fungal “shoe strings” can spread the disease.  It most frequently attacks trees weakened by environmental stress or other factors.

Unfortunately the shoestrings are often confused with roots. One of the easiest ways to recognize the disease is the white layer of mycelium that can be found under the outer surface of the roots or just below the bark at the base of the tree.

This fungal disease will sometimes produce small groups tan colored mushrooms near the base of affected trees.  Although not present every year the mushrooms most often appear in the early fall following rainy weather.

   

White mycelial fan on trunk

Fungal “shoestrings” on rotting stump next to infected tree

Disease Management:

·      Keep tree vigor as high as possible to avoid tree stress

o   Avoid planting trees in droughty or poor planting sites. 

o   Water trees, if possible, during extended periods of drought.

·      If found remove and destroy stumps and roots of affected trees.

·      Plant new trees as far as practical away from where an affected tree was removed.

·      Avoid planting new trees in a recently cleared woodlot that had a problem with Armillaria.

May 24, 2012

Springtime Late Frost and Freeze Damage

2012 Brought Weather Extremes in the Spring

Lilac in full bloom weighed down by snow – April 2012

Coming off a record mild winter, we had temps in Upstate NY  that reached 80 F in mid-March, the mid- to upper 80’s F in mid-April and then a low in the mid-20’s at the end of April.  May was drier than normal for most in upstate NY and in some areas we were about inch or more below the normal rainfall in May.

 

What does all this mean for growing trees? 

Frost and freeze damage was common especially in the low lying areas of fields.  This year it was about early warmth rather than late frosts.

Concolor fir – terminal bud killed from low temps

Spruce- bud, center, killed from low temps

It seems that there are enough surviving buds on trees in many locations, so trees will able to compensate for the lost growing points and little differences will be noted when pruning this summer.

Turkish fir – buds killed due to low temps

For those managing certain pests like White Pine Weevil, which must be controlled early in the spring, growers needed to be ready extra early and it was very short window of opportunity to get treatments in place.

If possible, this year’s new transplants could benefit from irrigation

 

The drier weather, during needle expansion, may make it easier to stay on top of the fungal needlecast diseases of Douglas fir.  But the lack of normal rainfall  is also stressing the transplants that were set into the fields earlier this spring.

 

October 5, 2011

Interior Needle Yellowing

We have heard from growers in upstate New York about interior needle yellowing particularly affecting their concolor firs. From the trees we looked at on two sites in upstate NY we have not seen any diseases or insects involved, rather just natural fall needle drop.   This is one of those years where the yellowing is  visible and dramatic on many trees.  In some trees it is less noticeable because there is more new foliage to hide the interior foliage that is on its way out.  On some trees the interior needles drop with an “off-green” color which is less noticeable.  This autumn needle drop is also visible on white pines in most years, this year is no exception.

In either case with some strong winds between now and late November the offending yellow needles should be off the trees and they will be ready for the Christmas tree shoppers.