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Healthy Fruit 2009 Vol. 17:14

Jul 21, 2009

The way I see it

The unusually wet weather pattern persisists. The biggest concern right now is disease pressure. In fact, the wet weather seems to be suppressing insect populations. (Anyone seem many potato leafhopper yet?) Conditions definitely favor both summer diseases in apple and brown rot as peaches and plums ripen. Be sure to maintain adequate fungicide coverage through this wet summer. This will mean shortening spray intervals compared to usual summer cover sprays.

I will be in Nova Scotia for the week of 02-Aug for the IFTA Short Tour. My plan is to provide regular reports on my blog.

The next Healthy Fruit will be published on or about August 4, or just check my blog.

J. Clements

Apple-crop brown rot control post

I am passing along this recent apple-crop post and replies (one from me) as it is certainly timely. J. Clements

Frank Carlson <fcarlson@carlsonorchards.com>

to Apple-Crop <apple-crop@virtualorchard.net>

date Tue, Jul 21, 2009 at 9:17 AM

subject Apple-Crop: brown rot on nectarines



We seem to have a brown rot problem in our JuneGlo nectarines. Has anyone had any experience in going in and cutting out the terminal growth tips which have an infected fruit and shows dieback looking like fireblight on apples?

Also, does the brown rot fungus get into the wood?

Frank Carlson

Carlson Orchards, Inc.

Harvard, MA. 01451

Win Cowgill <cowgill@njaes.rutgers.edu>

to Apple-Crop <apple-crop@virtualorchard.net>

date Tue, Jul 21, 2009 at 10:26 AM

subject Re: Apple-Crop: brown rot on nectarines



Frank - brown Rot can get into the wood. It can overwinter in the wood as well. Once in the wood it is very hard to control. I encourage gowers to remove all fruit at harvest, and leave no mummies in the tree. Any mummied fruit will ensure that brown rot can infect the twig.

Win

Win Cowgill

Professor and Area Fruit Agent

Department Head

Rutgers Cooperative Extension of Hunterdon County

New Jersey Agriculture Exp. Station

PO Box 2900

Flemington, NJ 08822-2900

Office 908-788-1338

Cell-908-489-0207

Email: cowgill@njaes.rutgers.edu

http://www.virtualorchard.net/win/

Jon Clements <clements@umext.umass.edu>

to Apple-Crop <apple-crop@virtualorchard.net>

date Wed, Jul 22, 2009 at 9:48 AM

subject Re: Apple-Crop: brown rot on nectarines



Frank, Dan Cooley once told me don't underestimate the importance of blossom sprays for brown rot, as that is when the primary infection really starts. Of course we have had a lot of wet weather this summer which is going to favor brown rot. You may have some sanitation issues that need to be dealt with. Win is right in that brown rot persists in shoots. Nectarines are generally more susceptible than peaches. Have you considered the fact you may have fungicide resistance? You appear to have a lot going against you.

My initial reaction is to cut out the infections, but now I am wondering if that could lead to more infection now that there is damage to the plant? Especially considering the wet weather pattern we are in. I would opt for maintaining excellent (and rotational) fungicide coverage.

And hope for some dry, sunny weather.

Jon

--

JMCEXTMAN

Jon Clements

clements@umext.umass.edu

aka 'Mr Liberty'

aka 'Mr Honeycrisp'

IM mrhoneycrisp

413.478.7219

Time to collect leaf samples for nutrient analysis

The next couple of weeks is the time to collect leaf samples for nutrient analysis. I suggest doing each orchard block every 3 years. Directions and where to send the samples can be found in the Soil and Plant Nutrient Testing Laboratorysection. J. Clements

Quintec supplemental label for powdery mildew on pumpkins

I know many apple growers also grow pumpkins, so I figured I would pass this along from Greg Comeau, Dow AgroSciences:

"Attached is the new Quintec (supplemental) label for Powdery Mildew (PM) on pumpkins. It is a dynamite product that all the distributor reps are familiar with and should be useful to growers if we ever get PM weather."

J. Clements

Guest Article

Japanese Beetle, Honeycrisp Apple, and Sunburn

Win Cowgill and Dean Polk, Rutgers Cooperative Extension

Reprinted from Plant & Pest Advisory, Fruit Edition, July 14, 2009

(Ed. note: Sunburn? Like we need to worry about that...:-))

Honeycrisp apples have turned out to be one of the more difficult apples to grow. Japanese beetles and deer prefer it and every disease in the book seems attracted to it. But the bottom line is the consumer loves it and continues to pay a premium price for it, up to $3 a pound in NYC city and select markets. Wholesale prices remain strong as well commanding $40 a bushel box.

Honeycrisp has turned out to be an indicator crop for Japanese beetle emergence. Japanese Beetles are slow to emerge this year; cool wet weather may have reduced the population. We saw the first ones on Honeycrisp July 13th, Hudson Valley growers saw their first the week before. (Note that Liberty apple is a close second as the indicator plant for Japanese Beetle.)

Control can be difficult on apple, Imidan is not particularly effective. Japanese beetles can reduce the leaf foliage significantly on Honeycrisp leaving them predisposed to sunburn on the skin. I believe they can even destroy enough foliage to reduce fruit set the following year.

In my Honeycrisp blocks at the Rutgers Sndyer Farm I have used Surround WP (Kaolin Clay) from NovaSource Corp, to greatly assist with control of Japanese Beetles. I have used this product for four years very successfully against beetles. The side benefit is that I had very had very little sunburn and very little disease on my Honeycrisp for the past three years. Washington state apple growers have used Surround for years to prevent sunburn, which is a labeled use of Surround. Consider using Surround WP next year in your spray control of Japanese beetle and sunburn on Honeycrisp.

Surround WP -- tips on use: apply as soon as you see the first beetles. Use the 50 lbs per 100 gallon rate for the first two applications to get a good coating, apply at 7-14 day intervals, no more than 14 days apart. Make sure that both sides of leaves are covered; apply 2 x for the first application if coverage is not thick enough to coat the fruit and leaves. Use adequate water to get good coverage. Do not use de-foaming agents. Surround is generally compatible with other pesticides but jar test first. Add the Surround to the spray tank first and agitate before adding other materials.

Use adequate water on oversprays to ensure penetration of materials.

Growth benefits -- when Surround is applied at labeled rates fruit color may be improved and tree vigor enhanced, both important on Honeycrisp. Read the label for more information.

Other Japanese beetle controls for apple are as follows:

Provado 1.6F@ 6-8 ozs.acre (7 day PHI), Assail (30S) @ 6-8 oz/A (7 day PHI), and Calypso (2-4 oz per acre) (30 day PHI), Avaunt (5-6 oz per acre) (14 day PHI), and Sevin and various pyrethroids. I would not use Sevin or pyrethroids on apples at this time, since they will likely cause mite problems.

More on Sunburn

Dr. David Rosenberger wrote the following in a previous Scaffolds Fruit Journal

"Most growers recognize sunburn when it shows up as browning or bleaching of the skin on the sunward faces of apple fruits growing in exposed positions within the tree canopy. However, internal fruit damage caused by high temperatures is less common. High ambient temperatures combined with solar heating of exposed fruit can cause breakdown of cells in the fruit flesh. The injury first appears as water-soaked areas on the fruit surface. Water-soaking is also evident in the fruit flesh if fruit are inspected soon after the injury has occurred. Because the damaged cells die and collapse, whereas non-killed cells in the fruit continue to grow, fruit soon become misshapen. Sections through the damaged fruit then reveal necrotic and collapsed tissues."

"Honeycrisp fruit damaged by sunburn or heat injury are especially susceptible to black rot, white rot, and bitter rot. The heat-damaged skin can no longer maintain the natural defense mechanisms that normally help to protect apple fruit from infection by these pathogens, so summer fruit rots may appear even where reasonable fungicide protection has been maintained through summer."

In New Jersey we know that sunburn followed by infection with both bitter rot and or white rot is a given on Honeycrisp, the goal is to prevent Sunburn and maintain adequate fungicide coverage to prevent bitter rot and/or white rot.

Jon Clements of UMASS has put together and excellent web page on Honeycrisp disorders.