Saturday, July 16, 2011

Hosta Pests - Fungus?

I am having three problems with hosta this year. I think it is fungus and / or viral.  Let me share pictures and what I have attempted to date for pest management. Any advice welcome, as you can see from prior post, since I have tons of hosta and would like to get ahead of these problems.  BTW I love this guide to hosta pests from IA extension.

PROBLEM 1: Brown Leaf spot, early spring issue

Brown spots on Hosta -Spring 2011

Post Treatment - much better!
First this this growing season I noticed these brown spots on hosta which grow up against the house facing south.  This flower bed is watered by run-off from the roof.  I do not typically water here.  When I noticed the brown leaves, I thought this was Anthacnose.  I checked in at the garden center and bought the recommeded fungicide. Noting to myself that I really need to apply it early next spring to avoid this problem.  First I picked out all the leaves with any sign of brown spots on them.  Then I've made two applications of the fungicide.  Here is the after shot below - I thought I was done and moved onto other parts of the garden..

PROBLEM 2: White Leaf spot, July 2011

 Just a week ago I realized that in the same hosta bed, I had a new type of problem.  In the picture on the left you can see the white spot on the leaf.  In the picture of the bed you can see how widespread this issue is.  In some cases the spots are really a loss of all the chlorophyll - the spot is sheer and see through.  It was first only on the leaves that were closest to the house.  I thought perhaps overly hot water coming off from the gutter. Then I noticed it seemed to spread to more parts of the plant.

OK some more details - it's only on the leaves not on the stems.  The soil is dry and the roots appear healthy.  There is no softness to the plant tissue, nor unusual aroma. The green color of the foliage is consistent and shos no mosaic, chlorosis or necrosis.

 I am at a lose for exactly what is causing this problem. So my plan of attack was to remove all the leaves that showed any whitness on the leaves.  I am going to water this bed tonight because the ground was very dry.  Then tomorrow I will also spray with fungicide.

(Post update - I believe this was caused by too much sunlight - burning the leaves. The sun is direct in this area, and it also reflects off the brick wall. I think this spot was much shadier years ago. I may have to think about changing the planting.)

PROBLEM 3 (and 4?): Necrosis  Yellowing, July 2011

1) Yellowing - needs water?
Most recently a few hosta scattered around my yard have shown signs of yellowing and a few leaves dying.  I think this is from poor plant conditions rather than a pest.  Specifically I think I need to be wtering more.
So I pulled off all the yellow/dead leaves and watered like crazy!

Yellowing - Needs Water?

More anthracanose?

I'm going to blame it all on global warming. I've lived here almost 10 years and never had these issues with hosta before. Last year it was all about slugs (ewww!) and I learned all about the beer jars and salting them. Luckily there are no slugs here this year, but this problem to me seems worst if only in that I don't know exactly what it is or how to fix it.

Anyone have any thoughts?

Today is all about improvization!

Keep Singing,

Teresa Marie

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