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Healthy Fruit 2009 Vol. 17:4

Apr 28, 2009

Current (April 27) degree day (DD) Accumulations

Location: UMass Cold Spring Orchard (CSO), Belchertown, MA

  • Base 43: 277
  • Base 50: 135

Significant upcoming orchard events based on degree days (Base 43):

  • European red mite egg hatch: 231–337
  • spotted tentiform leafminer 1st flight peak: 264–390
  • McIntosh at pink: 275–313
  • obliquebanded leafroller larvae active: 158–314

Current bud stages

Location
McIntosh
apple --
early pink
Bartlett
pear --
early white bud
PF-14 Jersey
peach --
bloom
Cavalier
sweet cherry -- early white bud

Belchertown
UMass CSO
(04/27/09)

McIntosh Apple Early Pink Bartlett Pear Early White Bud Jersey Peach Bloom Cavalier Sweet Cherry Early White Bud

 

The way I see it

It's June hot. In April. For several days. Unprecedented? Well, we are headed for the earliest bloom in years. I expect some orchards will have first king bloom open today. Which begs the question? What about fireblight? Probably minimal risk based on the fact it is suppose to cool off dramatically tonight, and first bloom seems less susceptible. No doubt it has been hot enough to ramp up the risk, and showers are forecast for tonight, but the final condition necessary for significant fireblight infection -- open bloom -- will not be met. My call at this point. Whew. That is not to say the risk could re-develop in the coming week(s), so stay tuned. Also, see the Guest Article on controlling growth and managing fireblight using Apogee.

What about scab? Well, we have only had one significant infection event since green tip in Belchertown. About 25% ascospore maturity and definitely entering the accelerated phase. With a minimal risk of rain tonight, we might get by without having an infection period. But showery weather is predicted for the upcoming weekend. Everyone will be applying fungicide targeting apple scab late week unless the forecast changes significantly.

Pink bug management. Pretty simple, Tarnished plant bug (TPB) rarely warrants treatment. Although with this hot weather, they may be very active. Pyrethroid insecticides, the best control option, are not really an option given their negative impact on beneficial insects. Non-pyrethroid options include Actara, Assail, Calypso, Lannate, Lorsban, Vydate, Beleaf. These would be good choices for both TPB and rosy apple aphid (RAA) if you have a problem with that insect. Spotted tentiform leafminer (STLM) are flying and laying eggs, but rarely is this generation worth spraying for. Probably best to just ignore the pink spray and concentrate on what's coming up -- petal fall.

J. Clements

Orchard fertilization update

Last week I was reminded of several facts sheets on the UMass Extension Fruit Program about nutrient management/fertilization of apple orchards. In particular:

 'All-purpose' ground/soil fertilizer application recommendation for mature trees growing well, which is:

For apples, apply a 10-0-30-5Mg-0.5B blend at 200 to 300 lbs. per acre. This delivers (per acre):

  • 20-30 lbs. Nitrogen
  • 60–90 lbs. Potassium (K2O)
  • 10–15 lbs. Magnesium (Mg, so often low in leaf analyses)
  • and 1–1.5 lbs. Boron

For peaches, step one, apply a 10-0-30-5Mg blend at 200 to 300 lbs. per acre in mid-late April. This delivers (per acre):

  • 20-30 lbs. Nitrogen
  • 60–90 lbs. Potassium (K2O)
  • 10–15 lbs. Magnesium (Mg, so often low in leaf analyses)

For peaches, step two, apply 20–30 lbs actual N per acre at shuck split. Use one of the following:

  • 125–185 lbs. calcium nitrate (15% N)
  • 60–90 lbs. ammonium nitrate (34% N)
  • 45–65 lbs. urea (45% N)

J. Clements

Brown rot/blossom blight control options

Mild, wet weather favors brown rot/blossom blight infection of stone fruit -- peaches, nectarines, plums, cherries. A reminder that last year's mummified fruit still in the trees is a significant source of infection. (See picture below! Arghh!!) Step one of IPM for brown rot it to get those mummified fruit out of the trees and onto the ground! Step two is to apply a fungicide during bloom when weather conditions favor infection. Fungicide options for brown rot/blossom blight are numerous. Resistance is an issue. Perhaps the best, most comprehensive reference I could find on fungicide options is on the Cornell University New York Agricultural Experiment Station website. For 2009, Quash (Valent) is also registered for control of brown rot in stone fruit (at least Massachusetts). I hope you find the above Cornell reference useful, and do consider applying at least one fungicide during bloom. That is one component of a season-long IPM program for managing brown rot in stone fruit.

J. Clements

Brown Rot Peach Mummies

 

 

Guest article

Apogee® for Fireblight Prevention and Growth Control in Apple Production (Win Cowgill, County Agricultural Agent, NJAES)

reprinted from Rutgers NJAES, Plant & Pest Advisory, Fruit Edition, April 14, 2009

One of the main reasons for using Apogee is for the prevention of the shoot blight phase of fireblight on high value apple cultivars. Consider Apogee use on high value fireblight susceptible cultivars especially when they are grown on fireblight susceptible rootstocks. However you have to begin applications early, from king bloom to petal fall (1-3 inches of growth).
Note: make sure to read our NJ suggestions at the end of this article.

Controlling the Shoot-blight phase of Fireblight
Controlling vegetative growth with Apogee will reduce the incidence and severity of fire blight infection (Erwinia amylovora) of shoots and leaves. Apogee does not have direct antibiotic activity against the fire blight bacteria (Erwinia amylovora), but Apogee can decrease host susceptibility.

Blossom Blight
Apogee does not control blossom blight. However Apogee can be combined with strep materials when used at bloom for blossom blight control according to Dr. Keith Yoder, Extension Fruit Pathologist at VPI. They do not interact. If conditions are favorable for blossom blight (rain and 65F plus temperatures) when you make your first Apogee treatment add Strep, if you have late bloom you may need to add Strep to your second Apogee application as well according to Dr. Yoder.

For maximum reduction in fire blight susceptibility, Apogee should be applied at least 10 days before the occurrence of weather condition favorable for shoot and leaf infections.

Apogee reduces the susceptibility of apple shoot tips to fire blight and should be used as one component of a comprehensive IPM strategy for control of fire blight. This decrease in susceptibility will not become effective until about 10 days after application. Once you see shoot blight it is too late to use Apogee.

Tree-Row Volume (TRV): Using Apogee as part of a management program significantly reduces the tree row volume. Spray guides typically recommend using the tree row volume to determine the correct pesticide application rates.

Timing and rates are important considerations with Apogee application. (As with any other pesticide or PGR!) First, you need to consider the amount of vigor in your orchard – high vigor will require higher rates to do the job. For timing, the most important application is the first – it must be made when terminals are 1-3 inches long, no later (bloom – petal fall). Subsequent applications are made at 7- to 14-day intervals depending on the vigor of the orchard. For moderate vigor orchards in New Jersey, 3 or 4 more applications are sufficient, whereas in high vigor or 'crop loss' orchards, up to 4 to 6 or more applications may be necessary to adequately control growth.

NJ Experience with Apogee
I have used Apogee at the Rutgers Snyder Farm on selected blocks for the past 8 years. We have had good growth control and minimal fireblight outbreaks on the blocks it was utilized. Since 2006 we have been utilizing a very low the 3oz rate/100 gal x 4 applications at TRV concentrated at 1.5x with good results. When this protocol is followed there has been minimal fireblight strikes.

Apogee may be an effective tool to help you reduce production costs, as you can reduce pruning bills, and increase pack out via better color and pest control. But, you must get effective vegetative growth control to realize these benefits.

Important Notes
Careful application and analysis of block-by-block cost/benefit must be followed to achieve the desired results with Apogee.

Do not use Apogee on Empire apples: Apogee can cause fruit corking and cracking when applied to Empire. The occurrence of this injury is sporadic, and the circumstances that lead to expression of the injury are not known. However, it has occurred across several years in Michigan, New York, Ohio, and Pennsylvania and NJ. Apogee has been applied to many commercially important varieties, but Empire is the only variety identified as being sensitive to Apogee.

Basics of Apogee Use
Apogee® (BASF Corp.) is a PGR (Plant Growth Regulator) for fireblight suppression and vegetative growth control of apples. The chemical ingredient, prohexadione calcium, blocks the synthesis of active gibberellins, the plant hormone that in part regulates shoot growth. Vegetative growth suppression with Apogee typically lasts for 2-5 weeks per application during the current growing season. Apogee does not affect vegetative growth the following year.

Apogee provides many beneficial effects including:

  • Reduced incidence and severity of fire blight of shoots (shoot blight). This decrease in susceptibility will not become effective until about 10 days after application.
  • Vegetative growth control
  • Reduced need for summer and dormant pruning
  • Improved light penetration into the tree canopy
  • Improved color of red varieties because of better light penetration into the canopy

Use a Water Conditioner
Mixing Apogee in hard water reduces its effectiveness. Adding either ammonium sulfate (AMS) or Choice as a water conditioner to hard water before mixing the Apogee resulted in better growth control than when Apogee was mixed with soft water. This result is important to growers who wish to use lower rates of Apogee to reduce undesirable effects on fruit set, or simply to save money.

In addition to conditioning hard water, AMS previously has been shown to increase the uptake of some chemicals, and this may explain why it improved the performance of Apogee in our study.
Note: In either case, our results suggest growers will get a better result by adding a water conditioner to the spray tank before mixing Apogee, even if the water source is soft.

The loss of effectiveness caused by hard water is due to the calcium it contains. It follows that one should not add calcium fertilizer to the spray tank when applying Apogee. Research conducted by Ross Byers in Virginia shows that tank-mixing boron with Apogee causes a similar loss of effectiveness. To clear up any confusion, hard water does not mean the same thing as high pH water. Dr. Byers' research shows no benefit from adjusting the pH of the spray tank before applying Apogee. It's the calcium in the calcium carbonate that creates a problem with Apogee, not the carbonate.

Hard Water – if your water is high in calcium carbonate the water may need to be conditioned. Add one pound of ammonium sulfate (AMS) for every pound of Apogee. Use high quality, spray-grade AMS to avoid plugging nozzles. Research at the Rutgers Sndyer Farm in 2000 also indicated the water conditioning products Quest and Choice could also be used effectively to modify the water hardness and improve the efficacy of Apogee. In our trial at the Sndyer Farm the addition of water conditioners AMS, Choice and Quest significantly enhanced the effectiveness of Apogee in reducing total shoot growth. The efficacy of Apogee can be greatly enhanced with the addition of water conditioning agents in high calcium hardness water conditions.

Specific Suggestions for 2009 Apogee Use

For Growth Control

  • Our suggestion is make four applications of the 3-ounce rate. Begin at 1-3 inches of growth bloom-petal fall, and repeat at 7-14-week intervals in North Jersey. After the second application the rate can be increased up t0 8- 12 ounces per 100 as needed depending on vigor and how much growth control is desired and how long you stretch between applications. I usually increase to 6 ounces.
  • More vigorous varieties and southern New Jersey growers may need a fifth application due to the longer growing season.
  • For just fireblight shoot phase control (younger trees) – one to two applications of at 6- 12 ounces per acre. With young trees we want them to fill in but we want the apogee effect of reducing shoot blight potential. Read table 3 on the current Apogee label. The rate can be reduced according to Dr. Keith Yoder if the multiple applications are made at the correct timing. If use the lower rate and miss the additional applications then you will not have control, as the shoots will re-grow.
  • Water Conditioner- Always use a water conditioner, Ammonium Sulfate (AMS)@ one pound/100 gallons –use the spray grade AMS
  • Adjuvant- always use a non ionic surfactant to improve leaf coverage
  • Do not use Apogee on Empire!
  • Do not use with Boron or Calcium, reduced efficacy may result
  • Be aware of the mixing order when combining with other chemicals, consult the label
  • Do a jar test of materials before combing in the tank, consult the label
  • Apogee is rain fast 1 hour after application
  • Note that Apogee should not be applied the same season with PGR's that contain Gibberellic Acids, these include Provide and Promalin. They may interact and prevent one another from working effectively.

Editors note: For other resources visit the UMass Extension Fruit Program website

J. Clements