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