For Immediate Release
Sarah Denkler
Horticulture Educator
April 27, 2008

Spring Showers Bring More Than Flowers

I have had many calls in the last two weeks about problems with flowering plants.  Be it a fruit tree, azalea or dogwoods, this spring has brought problems that we didn’t really notice during last year’s dry spell.  Although the list of potential problems is long, I would like to cover some of the more common that may be occurring with your yard.

Flowering Fruit Trees - The ornamental flowering trees have bloomed and leafed out beautifully but they may soon be demonstrating unwanted symptoms.  Because of the wet spring, followed by some hotter days, be on the watch for ‘Fireblight’ in your pears, crabapples, photinia and apples.  What you may see are brown or black leaves on new shoot tips that will then droop into a hook shape.  You may also notice cankers or sunken areas, on your tree branches that ooze.  This ooze helps to spread the disease as insects will move from infected to healthy areas as will water when it splashes from branch to branch.  Infected branches should be removed by cutting at least 6 inches below the canker and discarding.  When pruning, make sure to disinfect your pruners after each cut.  You can dunk your pruners in a solution of 70% alcohol or 10% bleach and water in order to keep them disinfected and prevent the spread of the disease.  Chemical products are available for application but they are usually cost prohibitive.

Bedding Plants – When you notice your bedding plants wilting and the roots turning brown you probably have ‘Root Rot’.  These are pathogens that attack the roots, killing them.  Because of the lack of healthy roots, your plant is not able to translocate water and it will wilt.  This problem begins to show up in March through June and again in August through October.  This pathogen may show itself if you have had soggy soil from the rain or from poor drainage.  This can also occur if plants are planted to deeply in the soil.  Improving soil structure and planting high in the soil profile can prevent this problem in the future.

Dogwood – The dogwood is precious to all Missourians as it is our state tree.  Spring would not be the same without those gorgeous colored bracts.  This tree can be affected by two common problems.  The first is the ‘Dogwood Borer’, an insect that feeds just under the bark, leaving small holes in the trunks that may be noticed when the bark sloughs off.  Watch for the borer holes to appear now through June.  Help prevent borer by helping the tree stay healthy, keeping it deeply watered and fed, or by applying insecticides (Permethrin) to the trunk and damaged areas for control. Permethrin treatment should be repeated at 6-week intervals 2-3 times.  The second problem that you may notice in dogwoods is ‘Anthracnose’, a common leaf fungus.  The flower bracts are usually attacked first, primarily during wet spring weather, and then the leaves may show symptoms. Small tan spots with reddish-purple borders can appear causing flower bracts and leaves to become wrinkled and distorted. As further infections occur, individual spots eventually merge to form larger spots and the centers may drop out. This fungus survives from year to year on infected twigs, fruits and other tissues.  Although it is usually not fatal, it can persist for years causing trees to become weak and more susceptible to other problems.  Several fungicides, including copper fungicides, can be used in the spring starting at bud break and continuing until leaves are fully expanded to help prevent the spread of the disease.

Azalea – One problem for azalea lovers is ‘Leaf Spot’.  It peaks in April and May, showing symptoms of scattered brown spots on leaf surfaces.  You may find a raised fungus in the center of the spot.  ‘Flower Blights’ also occur around this time, showing up in the same manner on your flower blooms, eventually causing them to turn brown and mushy.  The best way to prevent either is to keep the area clean of residue and prune to increase air circulation.  Azaleas like acid soil, tests should be done to confirm that the soil is between pH of 4.5 to 6.0.  There are also fungicides, like Daconil, that can be applied to prevent the spread of the problem. 

There are many other problems that can be found in our yards and landscaped areas.  I have picked a few to try to give you a heads up on what to expect as a result of our rainy spring.  Remember that the best defense in your yard is to use integrated pest management strategies to help stay ahead of potential problems.  This includes keeping your yard clean from debris and weeds, removing infected material and keeping your tools sharp and disinfected.  I hope this information helps and I wish you all happy gardening.

The Extension office is located in Kennett, Missouri at 101 South Main Street (the old bank) on the 2^nd floor.  Open Monday – Friday or you can call 573-888-4722 if you have a question.  University of Missouri Extension programs are open to all.

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Sarah Denkler, Horticulture Educator University of Missouri Extension P.O. Box 160, Kennett, MO 63857 573-888-4722   Denklers@missouri.edu