Friday, June 22, 2012

Ticks, bugs and disease, Oh my!



In the horticultural world, specific dates are not used to track insect hatches or plant blooms.  We use Growing Degree Days (GDD), which represents the accumulation of warm weather.  Very simply you average the high and low for a day and subtract 50 ( (H + L / 2) - 50 =GDD).  So once the high/low average daily temperature starts popping above 50 degrees everything starts moving...literally.  Insects and plants both develop based upon the accumulation of GDD.  Forsythia blooms in the beginning as we start counting GDD.  Korean Dogwood (Cornus kousa) start flowering around 300 GDD while Mountain Laurel (Kalmia laifolia) start flowering at 400 GDD.  Winter Moth, that troublesome leaf eater that is effecting our Maples, Birch, fruit trees and other ornamentals emerges at 20-50 GDD, while the Japanese Beetle that leaves brown patches in our lawns and chows on our roses start emerging at about 1,000 GDDs.  In the Route 128 suburbs we are well over 800 GDD as of now.  The last few days added about 100 GDD.


Enough of the science, why does this matter?  The weather determines when plants flower and when insects emerge not the calendar, and we are now getting into the time of year when things move quickly.
Let's start with the Japanese Beetles.  If you start to notice areas of your lawn that start to brown out or the turf pulls up easily in the next month, it is likely the result of Japanese Beetle Grubs chewing on the roots of your grass.  This is very common and often mistaken for summer dormancy.  If your lawn is properly irrigated it should not brown out.  Check the link above for more information or contact a lawn service company to manage the problem.  Not only will they chew on your grass as grubs, but when they emerge as beetles they will go to town on many of your favorite plant leaves, especially roses.  Another way to tell you have lots of grubs is to find areas in your lawn that have been dug up overnight by raccoons and skunks.  It looks like they have been clawing at your lawn.


Ticks are having a banner year.  If you are on your way to the Cape or up north, be prepared for a challenging year with ticks, especially the Deer Tick.  The link for this UMass help site gives you valuable information, especially if you want to have your tick tested.  Make sure you have repellent for your skin and clothing.  DEET for your skin and Permethrin for your clothing.  Most people in suburbia don't have to worry about their back yards, but if you are close to conservation land or wooded parks, local animals can bring them into your yard.  Check out this article on REI about proper care.  Sorry about the image of the engorged tick to the right.


Have you noticed lots of little  lawn mushrooms popping up in you lawn?  With the rain and lack of sun over the past weeks, the moist lawns became a good environment for various fungi to fruit.  This really can get out of control for lawns that have sprinklers that run while it is raining.  They are harmless to the lawn, but any mushroom should be considered potentially poisonous for consumption.  If you have little children, just mow them down or rake them out.  Once the sun and heat come, they will disappear.  If they are persistent and won't go away, you may have a cultural issue in you lawn such as too much thatch or organic matter.  Again your lawn company can help you with this issue.


Also with this past moist and cloudy period, Powdery Mildew has become prevalent on many plants.  It is harmless and looks like dusty gray powder but effects the look of your plants, especially as the season progresses.  It is very common on Lilac leaves in the late part of the summer.

Hemlock Woolly Adelgid is also having a good year.   There is a lot of confusion about this pest that I will try to clear up.  If you have Hemlock, a fine-needled evergreen,  on your property, take a close look at several of the branches.  Right now it is easy to see the white fluffy egg sacks if your trees are infested.  Because we had a mild winter the populations have exploded, and if you do not take care of the bugs, they will severely damage or kill your hemlocks.  Any good arborist can manage this problem with a very safe product called horticultural oil that smothers the sacks and insects.  It might seem like a bother to spend a couple of hundred dollars (depending upon the program and size of your property) every year to protect your hemlocks and other trees from disease and bugs, but healthy trees add tremendous aesthetic value to your gardens and property.

Andromeda and Azalea Lacebugs are plant sucking bugs that tend to leave the plants with stippled yellow or yellow leaves.  For the most part you can let these go in moderation, but plants in lots of sun will really suffer.  To find the bugs, they will be underneath the leaves.  They can be treated by you with horticultural oil and you have to work hard to get the oil underneath the leaves.

All of this can seem daunting, but there are many good arborists and lawn care companies that can take care of all these issues.  If you need to find a good company don't hesitate to ask them lots of questions and ask how they manage the use of chemicals.  A good company will use just the minimum number of chemicals to control issues on your property rather than broadcast their products on everything.

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