Horticulture Hotline 09/07/15
By Bill Lamson-Scribner
A little cool some mornings, but the beautiful days
continue. Rain, rain, rain. Mushrooms in lawns have become a hot topic. Do not
eat them and everything will be fine. Have you put out your preemerge for those
bothersome winter weeds? Have you fertilized your lawn, shrubs, and trees one
last time? Have fall army worms chowed on your turf? Have the mosquitoes driven
you indoors for the fall? With this rain, have you preventatively applied a
fungicide for your lawn in those areas you usually get fungus?
Gardenias, Azaleas, Magnolias, and many other evergreen
plants are losing some of their leaves. Although these plants are evergreens,
they still have some natural leaf drop this time of year every year. Crape
Myrtles, River Birch, Drake Elms, Willow and Sycamores are a few deciduous
trees that can begin leaf drop early depending on the health of the tree.
Since the chlorophyll has left the leaves, people often
mistake the yellowing of the leaves as a nutrient deficiency (most commonly
iron) or think their plant is going into a decline. The chlorophyll is the
“green” of the leaf, and usually masks the other colors of the leaf. Maple
leaves turn red in the fall because the chlorophyll that usually masks the red
color goes away leaving the red color behind.
As the chlorophyll leaves the leaf, bacteria and fungi grow
on the leaf because the leaf is starting to drop from the plant and the leaf is
not actively growing to ward off attack of these secondary invaders. At
Possum’s we get a lot of calls from people that feel like their plant has a
disease because of the leaf spots on the leaves that are getting ready to fall
off of the plant. There is usually no reason to treat these leaf spot diseases
that are attacking a leaf that is getting ready to fall off the plant anyway.
These diseases are different from the diseases that attack an actively growing
plant.
If you have a plant that is dropping leaves especially if it
is a new plant, check to make sure it was not planted too deep. Established
plants can end up being “planted too deep” because of mulch accumulation over
the years. When I worked in Hilton Head, I was involved in a large project at
the Lighthouse where azaleas were dying in large quantities from too much pine
straw being applied year after year.
Most plants do not like wet roots. If you have a plant that
is dropping leaves, check your drainage, and be sure the plant is not getting
too much water or the soil is too clayey.
A well fertilized plant will usually have less leaf drop.
Looking at crepe myrtles and azaleas really illustrates this fact. You have to
be sure you are looking at the same varieties of plant, and you can see a huge
difference in crepe myrtles in August and September depending on the fertility
program they are on. Now is a great time to soil test to get ready for 2016.
I’ll leave you with that!!
