26 June 2008
Water Logged Gardens and What to Do About Yours
Too Much Rain Causes Gardeners Pain
Weeds, insects and diseases are enough to make a gardener sigh. This year, rain is causing our problems.
Fortunately, gardeners are optimists.
We will do what needs to be done to save what we can and replant some of the rest. What cannot be salvaged or replanted we will try again next year.
Plant roots smother if they are in standing water long enough so move plants away from standing water, or create a line of drainage along the root line.
Plant leaf or foliage diseases are caused by fungi that reproduce and thrive in wet conditions. Beth Phelps, University of Arkansas Cooperative Extension services said the most important activity for a gardener when we have cool wet spring weather is to go look at your plants every day.
"Some disease problems favor hot dry weather and others thrive in cool wet weather," Phelps said. "By the time a plant is covered with powdery mildew or blight it is too late."
According to Phelps, powdery mildew on crape myrtle is cosmetic and spraying is not absolutely necessary.
"Powdery mildew on phlox, small dogwoods and hollyhocks can be deadly," Phelps said. "Pay attention. Look every day for fluffy white growth that looks like flour or baby powder. As soon as you see it, spray with fungicide."
In the vegetable garden, cooler, wetter weather can lead to nitrogen deficiency and later maturing tomatoes.
"The tomato ripening season lasts longer in cool weather which is a good thing," said Phelps. "Yellowing leaves may be caused by nitrogen leaching out of the soil. Add some extra nitrogen fertilizer to help them out. The other nutrients will remain; it's just extra nitrogen they need."
Root rot is a problem in wet clay soil because it retains too much water. Once you can see the effects of root rot, the damage to plants cannot be repaired.
"Drainage is a huge issue," said Phelps. "Two hours in wet, heavy soil and a tomato will be gone. In saturated soil, the space between soil particles is filled with water. Plant roots get no oxygen and the cells die."
Create drainage in areas where standing water could harm your garden. Either make a shallow drainage ditch along rows or put holes around roots to take water away from them.
"If it is still raining, making drainage holes will collect rain and make it worse," Phelps said. "When the rain stops, holes around the roots will pull that water out from between soil particles."
Bacterial blight in tomatoes is an annual problem not just in cool wet weather.
"To control disease buy any one of the fungicides on the market that are specifically identified for vegetables," said Phelps. "Follow the directions carefully."
Watch for mildew on perennials. Most fungal diseases need a day or two of uninterrupted moisture before they take hold and multiply. Consider pruning in the center to increase airflow.
Remove diseased leaves and dispose of them someplace other than the compost pile.
You may be seeing signs of Athracnose leaf disease in shade trees, especially on young leaves. Brown irregular spots and curled or distorted leaves are the visible signs. The tree may drop many leaves from the infection but Phelps said to not worry about it because it will not harm the tree in the long run.
Weeds are thriving now, too. In addition to robbing plants of much needed nutrients, they prevent desirable plants from getting airflow and provide mosquitoes with ideal breeding conditions. Soft, moist soil makes them grow but also makes them easy to pull.
Slugs and snails seem to multiply in wet weather. They eat holes in soft leaf plants such as lettuce, parsley and hostas.
"Reduce the number of hiding places for slugs in your garden," said Phelps. "If you have things in your garden like pots and art they will collect under them. The best way to control them is with commercial snail and slug bait."
Other methods such as beer traps, egg shells and diatomaceous earth are less reliable. Stagnant air around plants helps them reproduce; weeding and plant thinning help. Encourage slug predators to hang around your garden. Predators include frogs and toads as well as birds such as robins and blackbirds.
"Mushrooms are decomposers and when you see their fruit, they are doing their job," said Phelps. "You will have fewer spores in the yard if you knock or mow down the mushrooms but they do no harm if left alone."
Other signs of wet weather such as rust galls on cedar trees and oakleaf blister can be left alone, too.
If you decide to re-plant, wait until the soil has dried out. Damping off fungus that makes tiny seedlings fall over at soil level cannot be treated. If you decide to start new seeds for your tomatoes, cucumbers, melons, etc. start them in trays or pots and transplant later in drained soil.
To read Phelps’ Home and Garden articles go to www.uaex.edu/cgi-bin/sessearch.cgi?ae=%DF&q=phelps&op=and