Home > Great Big Greenhouse Blog > May 2016 > BONNIE'S GARDEN--Raindrops on Rose--Means Black Spots on Foliage

BONNIE'S GARDEN--Raindrops on Rose--Means Black Spots on Foliage

According to NBC12.com, this May is now the wettest May on record with 9.35”—so far.  We beat 1889’s record of 9.13”.  So what does all this wet mean for our gardens?  It means we might want to learn such ominous words as Anthacnose, Early Blight, Late Blight, Brown Patch, Black Spot, Septoria Leaf Spot and Powdery Mildew.

These are all fungal diseases that thrive in wet weather.  So here’s a quick overview.

Anthacnose attacks both deciduous and evergreen plants.  It’s characterized by dark lesions on leaves, stems, even flowers.  Leaves may drop prematurely.

Early Blight—large dark spots with yellow edges.

Late Blight—large dark spots with purplish edges.

Septoria Leaf Spot—small brown specks on foliage.  Leaves turn yellow and drop.

Powdery Mildew—looks like whitish film on foliage and can affect both mature and new leaves. 

Brown Patch—A lawn fungal disease characterized by patches of yellow and browning grass in your lawn.

Black Spot—Dark spots on rose leaves which eventually turn yellow and drop.

Yes, there are others, but these are most common.  What to do?  Number one, clean up weeds and debris in and around your garden!  These can host spores which can keep re-infecting your plants.  Be sure to avoid handling plants when they are wet because it’s easier to spread disease.  When pruning damaged or diseased foliage, clean pruners with alcohol before moving to another plant to avoid spreading  disease.  If it’s just a few leaves, try picking them off, otherwise treat the plant with a sulfur spray or Neem oil.

There are other things to remember: 

Be sure to dump extra water out of plant saucers on decks or patios—not just to protect those water-logged roots, but so that mosquitoes don’t have a convenient drop in which to lay their eggs.  Remember to check other places standing water can collect.

Check under those saucers (and under any rocks or boards near your garden) for slugs and earwigs.
For potted plants on decks AND for indoor plants (who haven’t been getting the sun they need) watch out for fungus gnats.  These are annoying little gnats flying around your plants, laying their eggs so the larvae can feed on decaying organic debris in the soil.  To get rid of them, add four tablespoons of bleach to one gallon of DAY OLD water (draw water the night before and allow it to stand overnight), then drench the soil.  This will kill larvae in the soil. 

Expect a few yellow leaves at the bottom of plants—not just from the abundance of water, but from the lack of sufficient sunlight.  Keep an eye on plants that like hot dry weather (like lavender, rosemary, and certain other herbs) for drooping new leaves.  This is not always a sign of lack of water, but often a sign of too much.  Check the soil before watering.

And for those of you with automatic sprinklers (like my neighbor down the street), CUT THEM OFF on rainy days!
Posted: 5/30/2016 by Bonnie Pega | with 0 comment(s)
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