From the Ground Up: Soggy, rainy conditions are stressing plants

flooding yard garden field iowa

Water extremes are starting to become the norm in Iowa. It is important to know what to do to counter the side effects of drought as well as excess water. Linn County Master Gardener Lisa Slattery fills you in on what to expect with all this moisture.


Q :What are the effects of too much moisture in our gardens and landscapes?
A : Rain barrels across Eastern Iowa are full and not too many gardeners have had to get out a hose.

The cooler temperatures have helped with utility bills, but all this excess rain and low temps are causing stress to our yards and gardens. Gardeners are noticing slow growth, spotting of plant leaves, rotting seeds, roots and stressed out trees. Fungus, bacteria and some annoying insects thrive in wet conditions. Plus, it's a doublepunch on our trees following last year's excessive dryness and high temperatures.

Many trees are showing signs of suffering the loss of what are called the fine roots or new roots that take in moisture. These fine roots dried up and died last year with no rain and excessively high temperatures. Without fine roots, trees can't take in adequate moisture, even though there is plenty. ISU Extension arborists expect to see adverse conditions that will affect tree canopies this year. There are already reports of leaf drop which is due to Anthracnose, a common fungal disease of trees in Iowa which affectsash, sycamore, maple, oak and walnut trees. Anthracnose thrives in cool, rainy weather.

ISU also expects to see more fungal diseases of fruit trees and spruces, as well as more rust type diseases on crab trees.

Conifers throughout our area are really stressed after several years of too much moisture, last year's drought and this year's cool wet spring. When conifers get too much water, their roots don't take in proper oxygen. This is referred to as 'wet feet' which will invite fungal diseases in many conifer varieties including Black Hills spruce, White fir and Arbor Vitae.

Vegetable gardens are also target for fungal diseases.

There are several fungus spores and bacteria that thrive in wet cool conditions, affecting almost every type of vegetable. Black Spot and Gray Spot disease infects 'brassicas' or cabbage, cauliflower, broccoli and brussel sprouts.

Early Blight and Septoria Leaf Spot are common fungal diseases of tomatoes. This year, tomato plants haven't grown much yet, making them more susceptible to fungal damage.

Garden slugs also thrive in wet conditions. So do some bothersome insects such as mosquitoes and gnats. Even though slugs are not considered insects, they require moist soil in which to lay their eggs and cool, moist, sheltered sites to hide during the day.

Mosquitoes lay eggs in standing water.

Mushrooms are also popping up in lawns and gardens.

But they will stop growing when the weather dries up and they don't cause permanent damage.

Most lawns should survive wet conditions; just avoid mowing wet lawns which leads to compacting your soil and spreading fungus. Lawns that have been flooded may not survive since standing water will drown grass roots, which require air to survive.

Lawns may be more susceptible to rust this year, but that should not permanently hurt the lawn. 



Questions on gardening? Contact Elizabeth Ward, eward@iastate.edu. 

 

 

 

 

article first appeared in The Cedar Rapids Gazette on June 16, 2013

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