Subject: Re: Peach tree leaf curl

From: [email-masked] (Jon Boy384)
Date: 28 May 1995 19:49:56 -0400

<My peach trees have had a leaf curl for the past coulple years.
The leaves look like they have cancer.  the growth on the leaf
encompasses about have the leave and bubbles up with red and
light yellow colration on the growth.  What is this growth
caused by and how can I treat it?>

Mark, I posted you the other day regarding your bout with leaf curl.
AFterwards I came acrossed this information on Pen Pages, a Gopher Site at
Penn State which adds some detail to what I had already told you. 

Again, good luck, 

Jon

PEACH LEAF CURL

Peach leaf curl is a fungus infection which destroys early peach leaves. 
Although new leaves develop, their growth reduces established food
reserves,
may reduce yield, and weakens the tree.  Defoliation by peach leaf curl in
successive seasons may result in the death of the tree.

SYMPTOMS

Infected leaves, which begin appearing in mid-May, are easily
distinguished
>from  healthy leaves since they are puckered and thicker than normal.  The
deformed area of the leaf is red to yellow at first and then brown. 
Eventually the infected leaves fall from the tree.

Spores of the leaf curl fungus overwinter on the surface of peach twigs. 
In
the spring, the spores multiply during periods of moist weather until the
leafbuds swell and open.  Rain is necessary for infection.  The spores are
carried on a film of water into the buds, where leaves are infected. 
Cool,
wet weather slows down leaf development and allows more time for leaf curl
infection.  Infection occurs readily at 50 degrees to 70 degrees F.  If
the
weather is dry during bud swell and bud break, leaf curl infection is
limited.

After the deformed and discolored leaves turn brown and fall, they produce
powdery-gray spores.  The spores are wind blown to the surface of the
peach
twigs, where they remain all winter.

CONTROL

Peach leaf curl is not difficult to control.  A single spray in the fall
after
leaf drop or in the spring before budswell will control the disease.  The
spring application must be made before bud swell.  Once the fungus enters
the
leaf, the disease cannot be controlled.

The fungicide kills the spores on the surface of the twigs.  For either
the
spring or fall spray to be effective, the application must be thorough. 
Complete coverage of the twigs, branches, and trunks is essential. 
Applications made from one side of the tree or with highly concentrated
sprays
may not be effective.

In commercial orchards Ferbam 76% WP (2 lb/100 gallons, 5.25 lb/acre) or
copper sulfate (7.75 lb/acre, 3 lb/100 gallons) plus lime (7.75 lb/acre, 3
lb/100 gallons) are the recommended fungicides for spring or fall
applications. 

For home orchards, 2 tablespoonsful of Ferbam per gallon of water in the
fall
or spring is recommended.

CULTURAL RECOMMENDATIONS

Where leaf curl is severe, maintaining tree vigor is very important:

1.  Reduce the demand on the tree by thinning fruit.
2.  Reduce drought stress by irrigating.
3.  Fertilize the trees with nitrogen fertilizer by June 15.  Be careful
not
to     overstimulate the trees.

__________________________________________________________________________
_____
NOTICE:  THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL
INJURY
OR
PROPERTY DAMAGE.

WARNING!  PESTICIDES ARE POISONOUS.  READ AND FOLLOW ALL DIRECTIONS AND
SAFETY
PRECAUTIONS ON LABELS.  HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED
CONTAINERS OUT OF THE REACH OF CHILDREN, PETS, AND LIVESTOCK.  DISPOSE OF
EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE.  DO NOT
CONTAMINATE
FORAGE, STREAMS, OR PONDS.
 
Where trade names are used no discrimination is intended and no
endorsement
by
Penn State Cooperative Extension is implied.

+-------------------------------------------------------------------------
---+
Author:  J. W. Travis, Associate Professor of Plant Pathology
Department of Plant Pathology, Penn State

---

From: [email-masked] (Michael Haynes)
Date: 4 Jun 1995 02:21:36 GMT

as someone with 400 trees,i can tell you my experience is that a fall 
spray after leaf drop with kocide 101 and again right before bud swell in 
the spring also with kocide 101 will give you a highly effective control 
of leaf curl.
-
  MICHAEL HAYNES  [email-masked]