Subject: Re: Biennial bearing of apples?

From: "M. Counides" <[email-masked]>
Date: 15 May 1996 07:41:01 -0700

I live in Idaho where it is very dry.  I do not spray my young apple trees 
(non fruiting) unless they show a problem. That would be like aphid damage 
or being chewed up by grasshoppers.  Once they start producing fruit they 
get lime sulpher and Imidan. Ooops, I do spray foliar fertilizer with 
trace elements on the trees.

Naomi Counides
Associated Beefalo of Idaho

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From: michael@helium (Michael Courtney)
Date: 15 May 1996 11:39:44 GMT

When I began caring for about 50 apple trees last July, they were heavily
loaded with frui and had been unpruned for several years.  The fruit was
slightly damaged with fungus and even though we removed most of the fruit,
I think it was too late as the fruit which remained never got very big.
Over the winter, we pruned the trees and got the orchard into shape.
This year the trees which were heavy with fruit have no flowers.  From
what I've read, I would tend to conclude that this is biennial bearing:
heavy with fruit one year, no fruit the next.  If this is a correct
diagnosis, can I expect heavy fruit next year which will need to be
thinned when it reaches 1" diameter in June?

Now that there will be no fruit this year, what kind of spray program
should I pursue.  I had planned a spray program consisting mainly of
captan/sevin with other fungicides/insecticides added if conditions 
warranted.  I had planned to begin the captan spraying at blossom time and
added the sevin when the blossoms dropped and the bees were out of the
orchard and repeated sprayings every two weeks.  Now that there will be
no fruit this year, what kind of spraying program is needed, if any?

--
Michael Courtney, Ph. D. 
[email-masked]

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From: [email-masked] (Lance Marshall)
Date: 16 May 1996 03:41:02 GMT

In article <[email-masked]>, michael@helium says...
>no fruit this year, what kind of spraying program is needed, if any?

Not that this will affect you this year but you should be aware that Sevin acts 
as a thinner when applied after blossom time (when the fruit is starting to 
become visible). If applied at this time and hot weather follows, you will get 
a heavy fruit drop...possibly too heavy with some varieties. Next year you may 
want to do this or preferably use a blossom thinning agent (depending on what 
is legal in your area) to break the biennial bearing cycle.

Lance

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From: michael@helium (Michael Courtney)
Date: 17 May 1996 17:32:11 GMT

Peter Worsley ([email-masked]) wrote:

: I haven't heard much about aphids on apple trees. I'm having terrible 
: problems this year (as usual) with gray aphids on one tree. These are not 
: rosy apple aphids or green apple aphids, they are gray, the same kind as 
: attack brocoli, etc. Many new leaves are curling up from being 
: attacked. There is heavy ant activity on the tree. I've sprayed about 5 
: times this spring with Rotenone and Pyrethrin, which hasn't really had 
: any effect. 

I've forgotten whether or not Rotenone and Pyrethrin are labelled for aphids.
Various insecticidal soaps are common for aphids and even some household
soap mixtures are reported to work.  Companies selling insecticidal soaps
for aphids often advertize in Organic Gardening magazine.

: I'm reluctant to go to anything more toxic, like Diazenon, 
: because I hope to sell some apples as organic at the Farmers Market. 

Yikes!  If I found out that Rotenone had been used on apples I bought
as organic, I'd be very angry.  Not that Rotenone is horrible, it
just seems dishonest to me to use non-organic insecticides and then
market the food as organic.

--
Michael Courtney, Ph. D. 
[email-masked]

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From: Peter Worsley <[email-masked]>
Date: Thu, 16 May 1996 17:45:06 -0700

>That would be like aphid damage or being chewed up by grasshoppers.

I haven't heard much about aphids on apple trees. I'm having terrible 
problems this year (as usual) with gray aphids on one tree. These are not 
rosy apple aphids or green apple aphids, they are gray, the same kind as 
attack brocoli, etc. Many new leaves are curling up from being 
attacked. There is heavy ant activity on the tree. I've sprayed about 5 
times this spring with Rotenone and Pyrethrin, which hasn't really had 
any effect. I'm reluctant to go to anything more toxic, like Diazenon, 
because I hope to sell some apples as organic at the Farmers Market. 
Today I finally got around to applying Tree Tanglefoot around the tree to 
control the ants. What exactly is the relationship between ants and 
aphids? Will the tanglefoot help? What should I spray with at this time 
of year (bloom is mostly over, fruit has set)? How about a dormant spray 
next winter? Thanks- Peter in Northern CA.

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From: Peter Worsley <[email-masked]>
Date: Fri, 17 May 1996 23:41:39 -0700

> I've forgotten whether or not Rotenone and Pyrethrin are labelled for aphids.

They are.

> Various insecticidal soaps are common for aphids and even some household soap mixtures are reported to work.  Companies selling 
insecticidal soaps for aphids often advertize in Organic Gardening 
magazine.

I've tried Safer insecticidal soap (contains Pyrethrin). Didn't work.
 
> market the food as organic.

If I'm not mistaken Rotenone and Pyrethrin are organic insecticides and 
are permitted by California Certified Organic Farming labeling 
guidelines. PW