Tar Spot

Tar Spot

What is it?

Tar Spot is a fungal infection that affects Maple trees. It's found to not cause any real damage to the tree, other than making it an eye-sore.

What does it do?

This fungus, like many others, overwinters on leaves from the previous year. The dead leaves on the ground release spores in the spring of the next year. These spores reinfect the maple tree or other maples nearby.

Do you have it?

This one's pretty easy to diagnose. Look at the leaves from your maple. Do they look like someone splashed tar on them? Like the pictures above? If so, you have tar spot.

How to manage it:

Since tar spot is not a damaging fungus, most cases are just ignored as they will nomally subside on their own. If it is something you cannot stand to look at, then you can call your local tree service company to see how much a fungicidal treatment would cost. The fungicides are the only thing proven to take care of tar spot. But make sure you call in the early spring because this is when the fungicides will be most effective.

Rhizosphaera Needlecast

Rhizosphaera Needlecast

What is it?

Rhizosphaera Needlecast, or Rhizosphaera kalkhoffii, is a fungus that affects spruce trees, most commonly Colorado blue spruce. It usually doesn't kill tree, however it does make them look sick. This is particularly devastating to tree nurseries or Christmas tree farms.

What does it do?

A spruce tree that has no issues will normally keep its needles for around 6 years. When one becomes infected with Rhizosphaera Needlecast, however, it may only hold the infected needles for one year. As with other diseases of conifers, the fungus starts at the bottom of the tree and works its way up. The reason this happens is because the ground under the tree is more susceptible to growing and sheltering diseases than the tree itself. 

It starts off by infecting the new needles in May or June, however it usually will not be noticeable until spring the following year. This is when the needles on the lower branches get a somewhat purplish hue to them (see above picture), then die off and start dropping. The spring rain then splashes the infection onto healthy needles, which restarts the cycle. This can sometimes kill the lower branches of the tree.

Do you have it?

Your first hint at a Rhizosphaera Needlecast infection will be when you see needles that appear to be purple when the sun hits them. The best way to find out for sure if your trees have it is to look at the infected needles under a magnifying glass. If they have hairy looking black spots on them, then there's a pretty good chance you found your disease. These black spots are actually the breeding grounds of the fungus, waiting for the rain to take them somewhere else on the tree. Here's what it will look like:

Photo credit: ohioline.osu.edu/hyg-fact/3000/3059.html

How to manage it:

As always, the best form of control is to know the disease before you buy a tree that might have it. If it's already in your yard, you're going to have to do a little more than that.

• If you have several spruce in your yard and only one of them is infected, make sure that you trim that tree last. The disease can be transmitted to the healthy trees just from the clippers. If you must trim your infected tree, be sure to trim that one last. Afterwards, sterilize your tools in a bucket of denatured alcohol for about 5 minutes.
• Try to keep the tree as healthy as possible. This includes vertical mulching, irrigation and aeration.
• Chemical: Since  Rhizosphaera Needlecast is a fungus, an applied fungicide could do wonders for your tree. Brands such as Daconil 2787 and Bravo might just do the trick for you. If you are goping to do it yourself, make sure to read all of the warnings and instructions. 
• Or you could always call your local tree care specialists.

Scab Disease

Scab Disease

Thanks to SPSnet

We've covered a lot of bugs in this blog, now let's tackle diseases.

What is it?

Scab disease is a fungal infection that harms and sometimes kills many fruit trees. Among the most susceptible are apple trees and crabapples. The main cause of this disease is a wet, cool spring. The fungus could come from surrounding trees or from a previously unknown infection on the tree the year before.

Little early to look this bare, eh?

What does it do?

The way it spreads: The fungus is intoduced to the plant by spores coming off of leaves on the ground from the previous year. The rain releases the spores which may end up on the living leaves of the tree. Once it gets on the leaves, it penetrates through to the susceptible tissue under a film of water. Then the fungus makes a different kind of spore and spreads to the rest of the tree, causing several health issues including:

• Dark areas on the leaves which can be purple, black or green and sooty or risen on the leaf itself
• Heavily damaged shoots will start dying back
• leaves turning yellow, often resulting in premature leaf-drop
• Budding hampered, sometimes the buds will turn black and hang on, even though they're dead
• "scabbing" on the fruit itself, making the fruit look rotten, cracked, or just plain inedible

Scabbing on the leaves of an Apple tree. 

This disease can make your trees look horrible. It changes the color of the leaves, makes them wilt, and often makes the leaves drop far before they are supposed to. It will ruin the fruit or make it drop before it's ripe. Not to mention, it's just unsightly to see a wilted, brown and purple, half covered tree.

How to manage it:

• The best way to deal with Scab Disease is, of course, to not have to deal with it at all. If possible, buy varieties of trees that are resistant to Scab disease. If you already have the trees, read on...
• To slow it down you can make sure that when the leaves drop, you get them cleaned up and destroyed as soon as possible. The dead leaves are what infects the new leaves the following year, so making sure they're gone will lower the risk of high infection. 
• The best approach is to hire a local tree care service to spray the trees with a fungicidal spray twice in the spring. This kills off the fungus and also may help keep other bugs from attacking the tree. These applications on average are one of the cheaper ones to get. 

Pictures thanks to: majestictreecare.com/Majestic_main/WebLinks/services.html

Gypsy Moth

Gypsy Moth

What is it?

The Gypsy Moth is another species of pest that was brought to the U.S. by accident. Since it's introduction, it has devastated much of the eastern states and caused roughly $868 million in damages. Starting as an egg being laid anywhere with protection during late fall, they hatch in the spring.

The larvae stage

What does it do?

During the first three stages of it's life (seperated by molting and growing in size), the larvae feed on the leaves of their host tree. In the first stage, they take tiny bites out of the leaves, just as much as they need. In the second and third stages they eat the leaves, from the edges to the center. This is the time that they are most damaging to hardwood trees, especially Oak trees. You usually won't see them active during the day unless the infestation is very dense. On minor cases, they feed on the top of the tree at night and rest during the day. If there is a large amount of them infecting the tree, you may see them active all hours of the day. In early to mid June they start building a cocoon. Usually these are located in bark flaps, under branches, basically anywhere providing good protection. When they emerge 7-14 days later, they are fully matured adults. They have now become the moths that we all know and hate. The males emerge first, and fly around look for a mate. The females (in most species) are flightless. Once the females emerge, they emit a pheromone to attract the males. After reproduction, they both die. And so the cycle repeats.

Adult male Gypsy Moth

Adult female Gypsy Moth

How to manage it:

You're best bets are killing the egg masses that you find on the trees or in some cases, anywhere else that provides protection. Destroying one egg mass can kill up to 1000 potential caterpillars. But there are actually a few ways to get these guys:

                                               

Hire an exterminator. Usually your local tree care professionals know how to deal with them and when.

Buy a gypsy moth trap. They can be pricey, but the may be worth it. 

Short on money? Luckily there's a few homemade tricks you can do to help:

Wrap duct tape around the tree at chest height, then smear "tanglefoot" on the duct tape. The caterpillars can try to cross it, but they wont get far before they get stuck.

Wrap some burlap around the tree and spray it with insecticides. As they cross it, it will soak into their bloodstream and kill them.

Using burlap again, wrap it around the trunk and flip the top half down, creating a barrier for them to rest during the days. Each day, go lift the flap and kill whats under it. This is the cheapest method, and works decently well.

Big thanks to http://www.gypsymothalert.com/control.html for the pictures and methods of removal!

Pine Needle Scale

Pine needle scale is a very common pest found in the US. It affects mostly Scotch and Mugo pines, but it may also attack firs, red and Austrian pines, and spruce trees. When looking at a mugo infected with scale, it looks like it has a light layer of snow on the needles. When you look closer, however, you'll see that the white specks on the shrub are actually shells, casing the scale inside.

Source: http://urbanext.illinois.edu/hortanswers/detailproblem.cfm?PathogenID=74

The scale starts off its life being hatched out of the mothers old shell around mid May. The first stage of their lives, they are flat nymphs that are known as crawlers. After hatching, they move to a suitable part of the same tree to hunker down and make their own shell. Some or them may fall off the tree or be taken by wind to another tree, which is usually how the infection spreads.  After finding a needle to call home, they create their own shell and molt inside of it, allowing them to grow for up to three weeks. At this point, the males emerge from their shell as a winged adult, and the females, after mating, lay as much as 40 eggs under their shell. Depending on where you live, they work two hatching seasons into a year. One in mid-May and one in late July. This can make containment difficult.

This picture shows the hard white shells of the adult scale, as well as the new-born nymphs, which apear here as small red dots. Source: http://msue.anr.msu.edu/news/pine_needle_scale_crawlers_should_be_hatching/

As far as treating scale goes, most effective controls have been systemic insecticides. They should be sprayed in June and in August, right as the newborn nymphs are trying to settle in, before creating their shells. Also effective horticultural oil sprays. Dormant oil sprays have proven for the most part ineffective. If you plan on trying these methods, contact your local pesticide dealer and ask for more information.

Evergreen Bagworm

The Evergreen Bagworm is a pest found in almost all of the US, as far west as Nebraska, North to New England, and South to the Gulf of Mexico. Although it's called the Evergreen Bagworm, it doesn't necessarily attack only evergreens. It attacks cypress, pine, juniper, spruce, locust, birch, black locust, apple, oak, willow, sycamore, poplar, maple, and several other species of plants and trees. Red Cedar and Arborvitae are their favorite food, and are attacked most often. In my career I've seen them on just about everything, from a metal stop sign to a plastic eves trough. They can wiggle themselves anywhere, but they only feed on plant material.

They start life out as a black larva, growing brown and tan as they mature. Inside the mothers empty sac from the previous season, up to 1000 eggs can be hatched. They hatch between early April and June, depending on the weather and the temperatures. When they hatch, they drop down from the mothers sac on a small piece of silk string, which usually gets caught by the wind, carrying the larvae to their host tree. Once they reach their new host, they immediately start forming their own case to live in, feeding off the tree and using its leaves to build its sac. It wraps its' silk around the branches of the tree, sometimes so tightly that it can hurt the tree just from the squeeze.

These are some pictures of bagworms that I found just today. They were on an arborvitae.

Adult males come out of their sac around late August, and look like a black moth with a 1 inch wingspan. The females, however, never leave their sac. They die in it, surrounded by the eggs that will be hatched in the next season.

The sac that you may see hanging off of your trees is made of silk, fecal matter, and pieces of the tree that the Bagworm is latched onto. Often times that sac is hard to spot to the untrained eye. Especially on spruces, they look just like pine cones and blend in very well. The camouflage tactics that the Bagworm uses is very effective in keeping away predators.





Ways to stop Bagworms from destroying your trees: 
If you find that you have bagworms, one of the simple solutions is to simply pull them off the braches you find them on. It's best to do this right before spring, as the female is already dead and the eggs haven't hatched yet. Make sure to throw them away in a sealed container, so that the hatching eggs have nowhere to go. Another option: fire. Burn the sacs as you pick them off.

The chemical solution is insecticides, and they should be sprayed mid to late June. Bagworm feeding slows in August, which means insecticides won't be as effective during late summer/fall. Make sure to cover the entire tree with the insecticides because you usually will not be able to see all of them. New larva are very small and hard to spot.