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nafex - Re: [NAFEX] Leaves curling and folding

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  • From: "Dennis Norton" <dmnorton@royaloakfarmorchard.com>
  • To: "North American Fruit Explorers" <nafex@lists.ibiblio.org>
  • Subject: Re: [NAFEX] Leaves curling and folding
  • Date: Tue, 27 Jun 2006 07:09:48 -0500

Sounds like you masy have fire blight. After hail storm damage, streptomycin should be sprayed immediately to reduce infection in the hail-induced wounds. Uptake of streptomycin is improved if applied during the evening. Streptomycin should not be applied within 50 days of harvest for apples or within 30 days of harvest for pears.
Fireblight is a serious disease of apples, crabapples and pears. Blossoms, blossom spurs, and branch tips are infected, turning brown and dying rapidly. The tips of branches often curl to form what resembles a shepherd's crook, or the curved end of a walking cane. The dead leaves remain brown to almost black and may remain on the branch all winter. The disease is caused by a bacterium that lives in the conducting or vascular tissues of the plant. The bacterium progresses down the diseased shoots and spurs, and sometimes reaches a larger branch where a dark or discolored area is formed. This discolored area is called a canker. The bacterium lives over the winter in young cankers with smooth, indefinite margins. In the spring, bacteria ooze from the canker, forming a sticky, thick liquid that insects feed on. These insects transmit the bacteria to blossoms, where new infections start. Later, the disease may spread from infected blossoms and old cankers to the shoots. Rain, wind, and hail help spread the disease.

Successful fireblight control requires a combination of actions. For the first step, overwintering cankers should be pruned away by cutting at least six to ten inches below the edge of the canker. Smaller diseased branches should be pruned about ten inches below the edge of the diseased area. Pruning is best done in late fall after leaf drop, when the diseased shoots can be readily seen since they retain their leaves. Or, pruning can be done in late February to early March. Pruning tools should be sterilized between each cut, Lysol diluted 3/4 cup per gallon of water, or household bleach diluted 1 cups in each gallon of water. Household bleach works very well, but corrodes tools, which must be carefully washed and oiled after use to prevent rusting. For the second step, apples or pears can be sprayed with streptomycin at blossom time. Use streptomycin at 50-100 parts per million every 3-5 days during blossoming. It can also be used every 14 days after blossoming, but streptomycin is not as effective for control of shoot blight as it is for control of blossom blight.

Fireblight is most severe on succulent shoots. Avoid overfertilizing trees, and do not fertilize in late spring or early summer. Hope this helps.

Dennis Norton
Royal Oak Farm Orchard
http://www.royaloakfarmorchard.com
http://www.theorchardkeeper.blogspot.com
----- Original Message ----- From: "sherwindu" <sherwindu@comcast.net>
To: <nafex@lists.ibiblio.org>
Sent: Monday, June 26, 2006 9:26 PM
Subject: [NAFEX] Leaves curling and folding


I just took a bunch of sample leaves up to my nearby Chicago Botanical Garden
plant information people and they had no solid answers as to what was causing
the leaves on my fruit trees (mostly apple) to curl up. There was no sign of
mites, and
it's past their season any ways. Some leaves at the tips of new growth shrivel
down
towards the underside of the leaf. This is seen more on the young trees, in
pots. I
try to keep them from drying out, but maybe they are getting too much water.
Other
trees in the ground have a tendency to fold up. I try to maintain an even
watering on
these trees, but it could be a case of too much or too little watering. There
is no sign
of insects or fungus. We have sprayed three times this year, the last being
about 3 weeks ago. The fruit looks fine, and the leaves look good except for
some hail damage from a few weeks ago. There can be two separate problems here,
but so far, I don't think the trees are in any great danger. The plant
information guy told me
to stick a pencil in the nearby soil and if it comes up dry, add water,
otherwise leave
it alone. Any thoughts on this?










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