Thursday, August 10, 2017 Vol 24:17 Insect Pest Update. Apple maggot fly on sticky red ball trap. Note the distinctive wing pattern and racing stripe behind the eye. Apple maggot (AM) populations vary greatly between locations. While it may be of some value to report on apple maggot trap captures in the Sanford to Bangor region if all the results were similar, that is not the case at this time. Overall AM captures are quite low for this time of year. Many locations have yet to catch a single AM on multiple traps per block. I attribute that to dry soil conditions during late July and so far in August. The drought in late summer 2016 may also be a contributing factor. That said, there are several monitored blocks that have exceeded the 1 AM per trap (per 3 week period) threshold. An orchard that received no insecticide in 2015, and had about half the block unsprayed 9j 2016 had an epic level of AM damage by September. That block is receiving insecticide for AM this year, but due to carryover from previous years, the traps should be overloaded with AM this year. That block is catching more AM than other locations, but the numbers per trap are in the single digits per week, which is not as high as I had expected. After almost all zeroes in previous weeks, the last two weeks have found a few other orchards catching 1 2 AM per trap per week. However, most blocks are still below threshold. So what do you do if you are approaching your final spray date without evidence of an over threshold AM population? My take on that is that the risk of late summer AM damage is too high, especially if rains and soil moisture returns resulting in an accelerated late season AM flush. Of course, you could hold on to the insecticide until there is demonstrated need (assuming you have traps up). But with peaches and early apple cultivars coming into maturity, most growers want to be done with insecticide applications. Even if trap captures remain low until your preferred final pesticide spray date, the safer course is to include an insecticide along with the final fungicide application. If trap captures remain low, the insecticide used does not have to have the highest efficacy rating. In that situation, Delegate, Entrust or one of the pyrethroids might be as adequate as Exirel, Assail, Imidan, Voliam Flexi or one of the pyrethroid + neonicotinoid premix products Endigo or Leverage. The other part of the equation is the even with codling captures also being low, a final mid August insecticide application may be keeping codling moth, leafrollers, white apple leafhopper and other potential pests in check even if AM pressure is lacking.
Speaking of AM traps, this year is a good example of their value. Growers with traps to reliably indicate lack of AM pressure have been able to save on a mid late July insecticide application. Using the traps is not complicated, you apply tangletrap, hang them up just before AM activity could commence, and count and remove the number AM flies you catch per week. If you catch more than an average of 1 AM per trap within a 3 week period, that is reason to establish or renew coverage with an insecticide effective against AM. After an application, you can discount trap captures while the insecticide coverage is still effective, (10 to 14 days, or 1.5 to 2 inches rain, see chart in July 25 newsletter). But that presumes the traps are positioned properly to attract AM. That is not rocket science either, but there are a couple of guidelines to remember: 1) traps should be visible from outside the canopy; 2) it is better for traps to have fruit below and on the sides near the trap. Female AM tend to hop from fruit to fruit, and the chance of capturing What you do not want to see apples heavily damaged by apple maggot egglaying and larval tunneling. AM increases if there are nearby; and 3) clean the traps so that they are not covered by other insects and debris. Trap capture efficiency goes down by about 25% over three weeks, the more exposed sticky red surface the better. Poorly positioned apple maggot traps Photos above: Trap not fully visible from outside the No fruit or foliage below the trap canopy **************************************************************** Well placed apple maggot traps Traps easily visible from outsides the canopy with fruit and foliage below and around the traps.
European red mites have also be remarkably low this summer. That is good because a high mite population is an unwelcomed addition to drought stress. I have lowered and simplified the thresholds. For August, mite control is recommended if more than 75% of mid shoot leaves near the trunk have living hatched mites present. Dead mites do not count. This threshold correlates with an average of 5 mites per leaf. With days beginning to shorten, those ERM that are present will increasingly lay eggs that will not hatch until next spring. Twospotted spider mites however, can blow up in late summer especially in dry conditions. So keep an eye out for mites on leaves and any bronzing. Late season bronzing does not automatically mean that the crop has been affected, but it is another stress factor, and bronzed leaves are less receptive to ReTain and other growth regulators. Asiatic garden beetle were numerous in several locations a few weeks ago, but in case you still find some, you can probably relax. There is only one generation a year. The larvae are important turf pests, but the adults are not known as significant apple pests and do not require control unless the population is enormous and is feeding on apple leaves. Foliar damage would resemble that caused by Japanese beetles. But Asiatic garden beetle is less focused on apple than Japanese Beetles, and has many of the other plants in its broad host plant range. But that host plant range could include apples. Fruit Maturity Plums Harvest completed: Early Golden, Spring Satin Ready now: Methley Ready soon: Obilnya and Shiro Color change is occurring in Caselton plum, but this variety is not ready to pick until later this month or early Sept. Asiatic garden beetle adult. Emmy Engasser, Hawaiian Scarab ID, USDA APHIS ITP, Bugwood.org Peaches Peaches are beginning their color change, but are not yet ready. Fruit size seems smaller than normal. Pears All varieties are still green and too firm for picking. Apples Pristine and other early apples should be ready now.
ReTain Application Dates. Estimated McIntosh harvest dates are listed in the table below along with suggested ReTain application dates. ReTain is a growth regulator that is useful for delaying apple and pear harvest and for preventing preharvest fruit drop. Before using any stop drop product, read the product label. Estimated date for McIntosh to reach starch index 4.0 and beginning of optimum harvest window for long term storage Estimated date for McIntosh to reach starch index 6.0 and end of optimum harvest window for long term storage Location Sanford Sept. 14 Sept. 22 Monmouth Sept. 18 Sept. 27 between Lewiston & Augusta Fredericton, NB Sept. 25 Oct. 3 ReTain application dates 3 to 4 weeks before normal ripening to delay first pick harvest by 7 10 days. ReTain application dates 1 to 2 weeks before normal ripening to slow ripening and delay drop of later picked apples (2 nd and 3 rd pick) Location Sanford Aug. 17 24 Aug. 31 Sept. 7 Monmouth Aug. 21 28 Sept. 4 11 Fredericton, NB Aug. 27 Sept. 3 Sept. 10 17 To delay the harvest the first pick by up to 7 10 days, apply ReTain three to four weeks prior to beginning of expected 1 st pick harvest date for untreated fruit. To prevent fruit drop and ripening of later picked apples (2nd, 3rd picks), apply ReTain one to two weeks prior to beginning of expected harvest date for untreated fruit. This later timing typically will not delay the start of harvest, but will slow down the ripening of the remainder of the fruit. ReTain can also be applied in a split application to control the ripening throughout the harvest period. ReTain may be useful to delay ripening for pick your own apples where customers are not expecting an early harvest or where warmer than normal temperatures inhibit red coloring. Where crop load is heavy, ripening can be delayed and color may be slow to develop. Gala and Honeycrisp are more sensitive to ReTain and can have a delay in ripening and fruit drop with lower rates. A split application of ReTain with NAA (PoMaxa, Fruitone or Fruit Fix) will work more than either material alone. For the split application, apply a tank mix of ReTain at half rate with 10 ppm NAA at 3 weeks before normal first pick followed by another tank mix of the same materials one week before normal first pick. Fruitone and PoMaxa have a 2 day preharvest interval (PHI); and ReTain has a 7 day PHI. Preharvest intervals for spray materials are listed in the Pest Management Guide, but the 2015 edition has an error for the PoMaxa PHI, so consult the label. ReTain is also labeled for plums and peaches. ReTain applications should be applied using a large volume of water such as 100 gallons per acre and a surfactant such as Silwet.
Conditions that Reduce ReTain Effectiveness: Drought Sunburn Heavy insect damage to foliage or fruit Mite infestations Severe apple scab or other disease History of bitter pit Rain within 8 hours of application Ethrel applied to neighboring trees More details on using ReTain can be found on the product label. To get the most out of ReTain, follow these additional recommended procedures. 1. Apply during slow drying conditions, early in the morning or late in the afternoon. 2. Apply ReTain at a rate of one pouch per acre, which contains 333 grams of product. ReTain comes in a water soluble pouch, and all of the material must be used once the pouch is opened. For Gala and Honeycrisp, use a reduced rate of slightly more than the half rate. 3. Use a surfactant. For optimum response, include one of the following: Silwet L 77, Sylgard 309, RNA Si 100 or BreakThru at 6.5 to 13 fluid ounces per 100 gallons (0.05% to 0.1% v/v of final volume). Use the low rate of surfactant if temperatures near 86 F are predicted. Avoid vigorous agitation since excess foaming could result. 4. Use sufficient water to get thorough coverage, but not runoff. For most trees this would be 100 gallons per acre or 2X to 3X. 5. The ph of the water should be in the range of 6 to 8. 6. Incompatibilities: Do not apply calcium chloride 4 days before or after a ReTain application that includes Silwet or Sylgard. Do not apply Retain with products that prevent sunburn. Application of ReTain with other chemicals is also not recommended.
Highmoor Farm / Pom. Soc. Field Day. Many thanks to all of you helped with the Summer Tour and Field Day at Highmoor Farm. The Maine State Pomological Society Gennaro Fazio, Cornell University and USDA ARS Paul Peters, Northeast Agricultural Sales Randy Drown, Crop Protection Services John Snell Joel Gilbert David Richmond Andy Ricker Mark you calendars for March 14, 2018 for next year s preseason tree fruit meeting in Lewiston. Orchard Calendar. Dates for Highmoor Farm in Monmouth.
Correction: While there has been some hail damage this summer, the report in previous newsletter about hail damage at Highmoor Farm and in Manchester was incorrect. More tomorrow on flyspeck / sooty blotch and some mysterious tree dieback. Closing Words. Sometimes you just need a second brain, even if it is a smaller one. ~ Maine apple grower explaining why he called me. I need more of me ~ David Baldwin