 Wilted yellow plants can be a
result of heavy rains
Recent
heavy rains left many with water logged lawns and saturated gardens. Add to that the
shredding effect of large wind gusts and hail that accompanied the rain, and you have
stressed plants. To state the obvious,
“Water always runs downhill,” this is okay until your vegetable garden is
drowning under an instant pond. Even the best
landscape plans don’t always account for where the water will go in a 100 year rain
event.
Some
people in southwest Michigan are also experiencing flooding in their basements and garages
compounding the frustration from recent rains. Plants
can overcome some stresses for several years, but combined with recent drought conditions
and this year’s the recent flooding some plants may find this to be too much. Many folks are seeing wilting and yellowing of
garden plants and an increase in certain fungal diseases such as Verticillium and Fusarium
wilt. These diseases are related to cool wet
then warm wet or humid weather patterns; very much like we are seeing this year.
In
the case of too much water, the symptoms often appear to be opposite of the problem. Our first response to seeing a wilted yellowing
plant is to think it needs water, so, we run for the sprinkler and water the garden. The solution is counter-intuitive to the problem;
you need to let the soil drain and the plant dry out a bit between watering. Most garden plants are satisfied with approximately
one inch of water per week. Annual
precipitation for Michigan is about 35 inches of precipitation per year. In the last two weeks we have received an average
of over 6.7 inches of precipitation and an overall average of 23 inches since April 1!
When
soils are saturated the water displaces the air in the soil and the plants are unable to
absorb oxygen through their roots. This sets
the stage for rotting and disease infiltration. Healthy and vigorous plants can withstand
an onslaught or two from Mother Nature, but weakened plants will show immediate signs of
stress. Extra water in the system will also
wash nutrients from the soil, keeping an eye out for nutrient deficiencies after multiple
heavy rains is advised. If you have a timed
irrigation system it can increase water inputs making the problem worse. Turn off your irrigation system during rains, and
keep a rain gage in your garden to measure irrigation as a supplement to rain.
Symptoms
of overwatered plants are:
·
Leaves
have or are becoming yellow from the top down.
·
Leaves
are drooping and dropping
·
Leaves
and flowers becoming dark or black in color quickly.
·
A
fuzzy mildew substance is seen on plants.
·
Plant
is not growing.
·
Plant
does not perk up when watered. (Note: if a
plant is under-watered and wilted too far this can also occur)
Also,
waterlogged soils force insects and small animals from the ground to get more air. It is
not unusual to see increased activity of many insect populations after a heavy rain. This can be inconvenient but settles down after the
soils begin to dry to natural states again.
Some
ways to help prevent overwatering of your plants:
·
Check
the soil moisture before watering or irrigating. A soil moisture meter can help, or dig in
a few inches to check.
·
Use
a rain gage to measure both sprinkler water and rain water.
·
Build
up your soil organic matter, this will both create air pockets for roots and retain water
for later use.
·
Know
your plants watering needs.
·
When
you do water, water in the morning so the moisture has time to dry and prevent mildew, and
water slowly so it can filter into the soil and not run off.
·
Watering
less often but more deeply will encourage deeper roots.
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