Needle Cast In Spruce

Do your spruce trees look like they have short pants? A little thin? You may have Needle Cast Disease and not know it!

Evergreens typically retain their needles for up to 3 years. If they are stressed or suffering from drought or disease they can lose them in one season. The investment the trees make in the needles costs them valuable resources and when they lose them prematurely they begin a downward spiral that may lead to death.

Needle Cast Diseases are fungi and in spruce trees they are generally two types,

Rhizosphaera needle cast or Stigmina needle cast. These are caused by Rhizosphaera kalkhoffii, and  Stigmina lautii respectively.These can be diagnosed by looking at the fruiting bodies on infected needles with a microscope or strong hand lens. Rhizosphaera fruiting bodies are rows of small smooth edged black dots coming out of the stomata, tiny breathing holes, on the browning needles. Stigmina fruiting bodies are black, in rows and are not as round or clearly defined as Rhizosphaera.

Infected needles will turn bronze and be dropped prematurely. This needle drop causes the tree to decline and look sparse. Eventually the tree may die. Wet humid conditions and lack of air flow all increase the chance of this disease spreading and damaging your trees.

Chemical fungicides are effective in controlling this disease. They must be applied according to label directions and typically two or three applications are required. When the needles are half elongated and when they are fully elongated is the recommended timing. These treatments will need to be applied on a yearly basis for several years until the plants recover. In the case of Stigmina this may be needed yearly.

Avoid watering on the foliage, keep groups of trees spaced well to increase air flow. Prune out dead branches and remove badly affected trees to limit the spread of the disease.

If you have questions Certified Arborists are industry recognized experts in plant insect and diseases control. Contact your I.S.A. Certified Arborist to see if you think you have this damaging plant disease.

European Pine Saw Fly

These gregarious larvae will wave in unison as you approach and resume munching on your Mugo pine as soon as you leave. This joint reaction is thought to deter predators from  the feeding colony.

The European Pine Sawfly, Neodiprion sertifer, is the larvae of a non-stinging relative of bees and flies. It is as its name would imply a native of Europe and was accidentally introduced into North America in the late 1920’s.

Young first instar, the larvae as it emerges from the egg, feed on new soft growth on conifers in late April to early May. As they grow they will move to feeding on older last year’s growth. The preferred host plants are two needle pines like, Jack pine, Scots pine, and Japanese two needle pines. They have been known to feed on red pines as well as white pines.  

The larvae feed in large groups of 40 to 200 individuals; this limits the effect of predators as well as creating local areas of intense feeding. This feeding can disfigure and even kill individual branches in specimen trees. Though seldom fatal too host plants repeated infestation can reduce the vigor of healthy trees and leave them susceptible to other diseases and insects.

Once the larvae grow and develop through a series of instars, larval stages, they migrate down the tree to the soil where they spin a cocoon. In the cocoon they transform into wasp like creatures. The adult forms emerge in September and October, quickly mating and laying eggs on the needles for next year’s generation.

The fertilized female lays groups of the small yellow, rice shaped eggs. These are  laid or glued as a sticky elongate coating on needles in the upper branches of the tree. The eggs overwinter, emerging to start the cycle next spring.

Control can be as easy as hand picking needles with eggs off the pines in the fall, or spraying them with a blast of cold water in the spring. Insecticidal soap is effective if applied to the early stages of larvae. Once the larvae are in the final instar, last stage before they descend, they have stopped feeding. This makes control ineffective. Chemical control is available and should be applied according to label direction.

If you have ornamental pines ISA Certified Arborists are industry recognized experts in plant insect control. Contact your I.S.A. Certified Arborist to see if you have this damaging plant pest.

For more information on this subject or any plant health care related questions please feel free to ask Professor Tree at the link in the right margin. 

Spots On Your Apples

 

 

 

 

If you would like to not have spots on your apples and leave the birds and the bees this article may be just what you’re looking for. Apple Maggot, Rhagoletis pommonella, is a small fly that infests a variety of hosts including crab apple, apples, plum, hawthorn, and occasionally apricots. It has a wide range from North Eastern United States through to Southern Manitoba, Canada

The spots on your apples are created when the female of the species punctures the skin of the fruit laying her eggs. The eggs then hatch and burrow though the apples causing the characteristic traces or brown discolored tunnels in the flesh of the fruit. The plant often responds by dropping infected fruit. Once the fruit is dropped the larvae emerge and pupate in the soil under the host tree. Some fruit remains on the host until fall and larvae develop at a slower pace in these fruits. This leads to a long period of emergence for adults in t the following spring.

Adults emerge the following spring just after the apples have finished blooming and continue to emerge for the next two months. The insects are small flies, slightly smaller than a house fly with black bodies and distinctive black bands on their clear wings. They emerge sexually immature and take a week to 10 days to fully develop. While maturing they feed on honeydew secreted by aphids. Once mature they congregate and mate on fruit.

The female lays as many as 300 eggs in her 30 day life span.

Control of this pest is difficult due to the long period of adult emergence. Chemical controls can be effective if applied at the very end of the flowering period and every 10 days thereafter until the adults are no longer emerging. Time applications to begin after flowers start to loose petals and you will have minimal impact on pollinators such as bees. Horticultural oils can reduce the population of aphids and limit food sources for immature adults. Bright red plastic sticky apples and yellow paper sticky traps can be used to scout for the emergence of adults. Culturally, prompt removal of all dropped apples throughout the season helps to break the life cycle. Dropped apples should be disposed of sanitarily off site. Removing alternate hosts in wild adjacent areas will also help to reduce populations. 

If you have questions about apple maggot contact your I.S.A. Certified Arborist to see if you have this damaging plant pest.

I.S.A Certified Arborists are industry recognized experts in plant insect and diseases control.

Canker Worms

It’s Raining Worms! 

Severe infestations of these pests can make it seem like worms are dropping from above! My first recollection of these insects was during a picnic in Lock Port when we had to sit far away from the elm trees to avoid these landing in our potato salad.
These pesky larvae are the rapidly growing off spring of two different insects. Spring Canker Worm, Paleacrita vernata and Alsophila pometaria , the Fall Canker Worm.
Between the two they can defoliate your trees faster than a late frost.
These indiscriminate feeders will dine on, apple, ash, beech, birch, box elder, elm, hickory, lindens, other maples and oaks.
The adult males of these insects are nondescript grey moths; the females are similar but are wingless and crawl up host trees to lay eggs. The larvae are 20 to 30 mm long, (1 inch) and can be green to reddish brown or black with several stripes along their bodies. Larvae inch along in a looping manner and are sometimes called inch worms because of this. There tube shaped bodies have small bumps or pro legs on the front lower side tat aid in identification. The Fall Canker Worm has three sets of these pro legs and the Spring Canker Worm two.
Damage occurs when the voraciously feeding larvae devour leaves, skeletonizing the leaves leaving only the veins and mid rib of the leaves. Several years of heavy infestation can lead to mortality in affected trees.
Adults emerge in the fall in the case of Fall Canker Worms and spring for the Spring Canker Worm. The Fall Canker Worm mates, lay eggs and dies shortly afterwards leaving their eggs to overwinter on the tree. Spring Canker Worms overwinter as pupae in the soil and emerge in spring as adults.
The wingless Spring Canker Worm females crawl up the tree and lay their eggs in early spring. Eggs from both types of insects hatch around the time of American elm bud break. They work their way out to the new foliage and begin feeding.
The wingless female is the key to success when it comes to using controls like sticky bands around the bark of  trees. Paper bands backed with insulation covered with sticky tangle foot stops the females as they migrate up the tree to lay eggs. These should be removed from time to time to prevent damage to the bark. When using them take care that the females have not formed a bridge allowing others to avoid being stuck in the sticky trap. Bacteria based sprays that work well on Canker Worms are available and can be effective if applied while the larvae are actively feeding. Chemical controls are also available check label directions for timing and application recommendations.
If you have questions Certified Arborists are industry recognized experts in plant insect and diseases control. Contact your I.S.A. Certified Arborist to see if you have this damaging plant pest.

Male Ash Flower Bud Gall Mite

 

This tongue twister of a pest with a passion for Fraxinus flowers has a curious life cycle.

A small mite, Eriophyes fraxiniflora can cause unsightly damage to your Ash trees.

To be clear this pest only attacks the Male flowers of the ash tree. Ash are a dioecious species, that being trees that have only male flowers on one set of individuals of the species and female flowers on the other set of individuals. Female ash trees bear copious numbers of winged seeds that can be a nuisance in the landscape. For this reason many people plant only male trees and this makes an abundance of available hosts for this pest.

The damage from this pest, twisted brown galls are most visible in the dead of winter, but the injury occurred months earlier when the trees flower in spring.  The normal progression is for the flowers to fall off the tree once they have completed flowering. However as the summer progresses the distorted mite damaged flowers remain on the tree and turn into unsightly brown balls. While the trees will not be killed by this activity their twig growth will be very distorted.

The mites become active as new tissue emerges in the spring and they begin to dine on unfolding tissue. They secrete tissue distorting chemicals as they feed and the ash tree forms galls.

Control of these pests can be difficult but early season horticultural oil will provide some control if applied when buds first break. Similarly miticides applied at this time will control these pests. Ash trees flower early in spring and care must be taken to time the applications correctly.

Ash trees are currently under pressure from the potential of Emerald Ash Borer infestation and are not recommended for planting. Keeping them healthy and growing strong can help protect them from other insect infestation.

If you have questions, Certified Arborists are industry recognized experts in plant insect and diseases control. Contact your I.S.A. Certified Arborist to see if you have this damaging plant pest.

Frost Cracks and Sun Scald

Winter’s severe cold weather takes its toll on all of us and trees are no exception.

Frost cracks are thought to occur when trees differentially heat up and cool down in winter.

This uneven cooling and heating sets up stress inside of trees and the result is a frost crack.

Heating and quick cooling can also cause the phenomenon of sun scald.

Sunscald and frost cracks normally occur on the south and south west sides of young trees.

In the winter the sun is at a low angle and shines on the bark of trees warming the surface as the day progresses. Large swings in temperature occur as the sun sets and the bark rapidly cools.

The stress caused by differential heating can cause the tree to split outright, as is the case with frost cracks or just damage the living cells in the cambium layer and result in sun scald . The cambium is a layer of growing and dividing cells just under the bark but above the hard wood of the tree. When the cambium is damaged the bark will crack and peel off leaving dead regions of trunk.

Once a frost crack occurs and the tree is split there is no chance it will rejoin and “heal”.

The crack itself allows fungi and other pathogens to enter in to the heartwood of the tree and can lead to decay. While this does lead to a reduction in strength it does not always lead to failure, immediately or in the near future. Trees with this condition can live for many years and be effective elements in a landscape. If the tree is close to structures or areas where people sit it should be inspected regularly and well maintained. The tree responds by trying to grow over the crack, however the growth itself pushes the crack wider. In the end the tree may fail prematurely but not unexpectedly if your Arborist has pointed this out.

Sun scald damages large areas of cambium in newly planted trees and they should be considered for replacement.

Wrapping newly planted trees with white paper and protecting the trunks of trees with understory plantings are two solutions that can be used for new plantings. Be sure to remove paper wrappings once the threat of frost has passed. Once trees are established you may not have to wrap them. Over pruning, or lifting of young trees will contribute to damage from the sun so use caution when removing the lower branches from young trees. If you have a planting project in mind or suspect you have sun scald or frost cracks contact you I.S.A. Certified Arborist.

I.S.A Certified Arborists are constantly updated on the latest planting and pruning methods backed up by scientific research on tree wound response.