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Insect Pest Control in an Early Season

Posted: March 23, 2012

You probably have heard it a thousand times already but the degree days base 43°F accumulation for March 23 in southern Pennsylvania is about 4 weeks ahead compared to previous years (or 3 weeks compared to the 2010 season). Since most of us do not have first hand experience with such an unusual season, what it will mean to our orchards remains to be seen.
Dr. Greg Krawczyk and Dr. Larry Hull
Penn State Fruit Research and Extension Center Entomologists

 

 As of current insect observations, yesterday (March 22) was the first day of capturing Oriental fruit moth (OFM) (normally it is around mid-April).  It is the second week of collecting redbanded leafroller (RBL) and spotted tentiform leafminer (STL).  Since we need at least a couple days of sustained flight to establish a biofix, it is difficult to decide right now if March 23 will be the biofix date for OFM.  We will have to wait and see how consistent this trend will remain.

 

Historically, the bloom of apple trees is the time when both CM and TABM start their first generation flights; however during the 2010 season, which granted us a mid-April bloom of apples, the CM and TABM biofixes were not established until about 2 weeks after the bloom.  Although pheromone traps are needed during the entire growing season to assess population levels, the precise detection of initial moth activity during the spring is necessary for better timing of available control measures against those pests.  Therefore, this year we again strongly, strongly suggest placing pheromone traps in the orchards much earlier, so the biofixes can be precisely established.  A moth count of zero is a number, and actually in certain situations it can be a very good one.

 

Similarly, the brown marmorated stink bug (BMSB) adults also started early this season and already are leaving overwintering sites and initiating early feeding on available green plants.  Unfortunately, the movement from overwintering sites is a very extended process and could last for another 10 weeks.  In consequence, while within 2 to 4 weeks the adults could become reproductively active, most likely there will still be plenty of overwintering BMSB adults that still remain in a non-active phase.  So at this time, unless strong evidence exists for the actual presence of BMSB in orchards, no specific control measures should be applied.  Additionally, our around bloom pest management activities directed against other pest species should provide at least some control of BMSB.

 

In the next few issues of the Fruit Times Newsletter we will present more detailed brown marmorated stink bug management recommendations based on information generated during last season.

 

The following updates are normally posted in the April issue of the newsletter but this year we decided to deliver them earlier.  Although the early spring timings for insect management activities historically are based on phenological phases of tree development, in such an unusual year as this one, the actual on site monitoring of various pests should be the only valid pest management decision tool.

 

Protecting Bees and Other Native Pollinators

Although some insecticides are legally allowed as an application during the bloom (with various restrictions), the pest complex that can be controlled during that time period [obliquebanded leafroller (OBLR), European apple sawfly (EAS), rosy apple aphid (RAA), Oriental fruit moth and plum curculio (PC)], in most cases, can also be controlled at other, less controversial timings.  Therefore, due to continuous concerns with the possible insecticidal effects on honey bees and other native pollinator populations, we recommend that growers not use insecticides until the bees are completely removed from the orchards.  This season especially, due to this unusual weather pattern, our native pollinators may be the best we have for effective pollination of our crops.

 

Petal Fall Insect Pest Control

Oriental fruit moth, plum curculio, mites, aphids, leafminers, some leafrollers (OBLR) and to some degree scales are the insect pests that normally should be controlled at petal fall.  The application of insecticides during the petal fall period still remains one of the most important treatments, setting the tone for the rest of the season.  The combination of OFM, PC, European apple sawfly, oblique banded leafroller and redbanded leafroller (RBLR) should be controlled at this time by broad-spectrum insecticides (e.g., organo-phosphates; or neonicotinoids (Assail, Calypso); or Avaunt). Older neonicotinoids (imidacloprid containing products or Actara) applied at the petal fall timing will provide excellent control of aphids and leafminers but they will not control many other pests, although both provide good contact activity against brown marmorated stink bug (if present in the orchard) and some against plum curculio.  If only leafrollers, OFM and leafminers are the intended target(s) of the application, then an application of Intrepid, Proclaim, Rimon will also be very effective.  With expected, in season increase in usage of broad spectrum, not selective insecticides, the suppression of European red mite population after bloom might significantly help to manage this pest later during the season.  Agri-Mek with a penetrant (i.e., oil) applied at petal fall, in most cases still offers excellent control of ERM and STLM, and fair to good control of white apple leafhopper (WALH).  Agri-Mek should be applied before the leaves harden off, generally within about 10 days of petal fall.  Other acaricides such as Acramite, Envidor, Portal, Kanemite, Nexter or Zeal, although registered mainly for summer mite control, can also be considered for mite control at this time of the season.  The ovicidal acaricides - Apollo, Onager (Savey) – can be applied during the petal fall to first cover period.  Please see the recommendations in the new 2012-2013 Pennsylvania Tree Fruit Production Guide for rates of all products. 

 

Control of Scale Insects

San Jose scale overwinters as immature blackcaps on the trunks and scaffolds of the tree.  The nymphs remain dormant under their waxy covering until the sap begins to flow in the spring, and they continue to feed until bloom.  Scales are especially difficult to control on large trees with rough bark.  Growers who found fruit infested last fall with scale or who noticed scale infestations during the winter pruning, should apply the appropriate measures during this time of the season.   To provide successful control of nymphs an application of oil with an insecticide (i.e., chlorpyrifos, Esteem or Centaur) is necessary at the delayed dormant or early pre-bloom period.  If needed, another application of Esteem, Centaur or Movento applied after bloom (up to second cover) also should help in management of this pest.  Addition of oil is always necessary with applications of Centaur or Movento, while Esteem can be applied without oil.  Similarly to early season mite control, the secret to good scale control is good coverage.  Growers should use a minimum of 100 gallons per acre (GPA) or more depending on the size of their trees.

 

Please remember that the new language on the label for all products containing chlorpyrifos (e.g.,Lorsban) allows for only a single application of per year either as a dormant/pre-bloom or trunk spray during the season. 

 

Seasonal Activity of Fruit Pests

2012 season-weekly captures of adult moths in pheromone traps located at PSU FREC Biglerville, PA (Adams County):

 

Species        3/16   3/23  

RBLR             26    143

STLM              -    109    

OFM               -      3

 

Key to acronyms: RBLR - redbanded leafroller; STLM - spotted tentiform leafminer; OFM - Oriental fruit moth.

 

Degree Day Table

Accumulated degree-days base 43°F from Jan 01 for each reported year (courtesy of SkyBit, Inc.). The accumulated degree-days for the last date of the current year (March 31) mentioned in the table are based on the weather forecast.

 

Site/Date              03/31    04/07    4/14    4/21    4/28   

Biglerville, 2012        415       -         -         -        -

Biglerville, 2011        138      179     245     338     454

Biglerville, 2010        194      334     412     486     562    

Biglerville, 2009        157      210     242     305     439    

Biglerville, 2008        137      178     255     355     472    

Biglerville, 2007        213      249     259     290     394    

 

 

Rock Spring, 2012     323       -         -        -        -

Rock Spring, 2011       78       96     147     203     293

Rock Spring, 2010     141      277     342     408     463    

Rock Spring, 2009     116      156     173     226     349    

Rock Spring, 2008       61       88     146     240     352    

Rock Spring, 2007     147      189     192     218     300