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A Relatively “Normal” Year for the Development of Insects

Posted: April 21, 2011

If not taking into account the volume of rainfall we are receiving during this early part of the season, the degree-day (DD) comparison between this season and previous years suggests that DD accumulation (base 43) since January 01 is similar to DD accumulations observed during the last few years, with the exception of last season, when at this time we were already at petal fall stage on apples. Monitoring of insect pests in pheromone traps also suggests a relatively “normal” year for the development of insects.

Dr. Greg Krawczyk and Dr. Larry Hull, Penn State FREC Entomologists

Early Season Insect Activity

The biofix dates (first sustained flight for the season) for redbanded leafroller (RBL) (April 05) and spotted tentiform leafminer (STL) (April 06) occurred within a few days of the dates they occurred during the last few years (except for 2010). The Oriental fruit moth (OFM) situation is slightly more complicated - the first moths were collected during the week of April 10, but due to lower temperatures during the days following this capture, no additional moths were observed in traps until April 19. Then additional adults were observed in traps during the following two days. Unless we experience another string of cold days, the suggested OFM biofix for the Biglerville area will be April 19. The vast majority of OFM’s first generation flight and egg laying activities will most likely be directly related to moths active after April 19th, not the smaller portion of total OFM population active during the earlier part of the month.

It is expected that the biofix dates for codling moth (CM) and tufted apple bud moth (TABM) will be established within the next 10 to14 days (early May). Historically, the bloom of apple trees is the time when both CM and TABM start their flights. Although pheromone traps are needed during the entire growing season to assess population levels, the precise detection of initial moth activity during the spring should be helpful in better timing available control measures against those pests.

Brown Marmorated Stink Bugs Just Leaving Their Overwintering Sites

The brown marmorated stink bug (BMSB) adults just started leaving their overwintering sites and initiating early feeding on available green plants. Unfortunately for us, it is a long, not well synchronized process and most likely it will last for another 4 to 6 weeks. In consequence, while sometime in mid-May we may start seeing BMSB eggs and young nymphs developing on some plants, most likely there will still be plenty of overwintering BMSB adults that remain in a non-active phase. Also, with so many alternative hosts available for BMSB to support their development, it will be very difficult to predict the best time to apply any particular control measures. Each individual orchard, often even each individual block within the orchard, will have to be monitored separately and BMSB management options decided based on in situ observations. The efficacy of various insecticides against BMSB adults assessed during laboratory direct topical bioassays and various management options are presented at: http://extension.psu.edu/fruit-times/news/2011/latest-research-results-on-bmsb-control (G. Krawczyk’s presentation from April 14, 2011 Twilight Fruit IPM Meeting at PSU FREC).

In the next issue of the Fruit Times newsletter (May 2011) we will present more detailed brown marmorated stink bug management recommendations based on information generated during this past winter.

Avoiding Spray Applications During Bloom

Although some insecticides are legally allowed as an application during the bloom period (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 (OFM), and plum curculio (PC)] in most cases can also be controlled at other, less controversial timings. Therefore, due to the current 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. An effective, well-timed application of insecticides at petal fall should be adequate to control most of these pests.

Petal Fall Insect Pest Control

Although it appears that BMSB stole most of our attention during the winter time, the fruit pest complex still includes all other insects we normally had to manage: CM, OFM, TABM, PC, mites, aphids and so on. 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, EAS, OBLR, and RBLR should be controlled at this time by broad-spectrum insecticides (e.g., organo-phosphates; or neonicotinoids (Assail, Calypso); or Avaunt). Older neonicotinoids (Provado, 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 BMSB (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 the expected in-season increase in usage of broad spectrum, non-selective insecticides, the suppression of European red mite (ERM) 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 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 PA Tree Fruit Production Guide (http://agsci.psu.edu/tfpg) for rates of all products. 
 
Codling Moth Management for 2011

Codling moth remains one of most difficult pests to manage in our apple and pear orchards. The featured article in last year’s April issue of FTN (http://extension.psu.edu/fruit-times/news/2010/ft2904.pdf/view) provided a detailed overview of recently registered insecticides and their positioning for control of our standard fruit pests. Although mating disruption still remains one of the most effective methods to control internal fruit feeders (i.e., CM and OFM), this year due to the expected pressure from invasive Asian stink bug, BMSB, your choice of pest management programs may include relatively higher reliance on various insecticides. If your plan is to use insecticides for CM control, your choice of products this year should also depend on the stage of CM you wish to target. Products that possess ovicidal activity (i.e., affect the eggs) should be applied as follows: Rimon® (20-30 fl oz/acre) – apply within 100 to125 DD following biofix and repeat the application 14 days later; Intrepid® (16 fl oz/acre) – apply within 150 to175 DD after biofix and repeat 14 days later. Insecticides that target the hatching larvae (i.e., 250 to 350 DD after biofix) are as follows: organophosphates, various neonicotinoids (e.g., Assail®, Calypso®, Belay®), Avaunt®, Altacor®, Belt®, Tourismo®, Delegate®, and Voliam Flexi®. It is worthy to note that two listed neonicotinoids—Assail and Belay and Voliam flexi (due to inclusion of thiametoxam, an active ingredient of Actara)—also provide good direct contact activity against BMSB. Growers looking for a different approach for the control of CM can consider using CM mating disruption and codling moth granulosis virus (CpGV) (i.e., Carpovirusine and Cyd-X). For CpGV products to effectively control CM larvae, the virus must be ingested by the feeding larvae. 

Pheromone traps should be used to monitor adult insect pest populations in every orchard. The traps are very important for setting biofix, determining the seasonality of adult flight, and they also can help to estimate the relative adult population density in the monitored area.
 
Pear Psylla Update

Usually, at the petal fall timing, all stages of pear psylla (PP) (i.e., eggs, nymphs, and adults) are present on infested trees. For proper monitoring during the petal fall period, at least 10 leaves per tree (5 spur and 5 recently expanded shoot leaves) on a minimum of five trees per block should be examined. The action threshold is 0.5 nymph per leaf. The application of Agri-Mek (20 fl oz/acre) still remains one of the best PP control options at petal fall to PF + 10 days. A penetrating surfactant (i.e., a summer oil at 1% concentration) is a necessary addition to Agri-Mek in order to provide the best residual control. This spray should be applied in at least 100 gals of water per acre. After this window, Agri-Mek may not provide as effective control. Actara, Calypso, Centaur, Delegate, Movento, Provado, and Nexter also can be used at this time if additional control options are needed. Another option for PP control is the use of the kaolin clay, Surround®. If a good coverage is achieved, Surround (applied at 25-50 lb/acre) can represent a very effective additional tool for PP control and a possible repellent for BMSB.

Control of Scale Insects

San Jose scale (SJS) 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 with scale last fall or who noticed scale infestations during 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 gal/acre or more depending on the size of their trees. 
 
Seasonal Activity of Fruit Pests

2011 season weekly captures of adult moths in pheromone traps located at PSU FREC Biglerville, PA (Adams County): 

Species

3/25

4/01

4/08

4/15

4/22

RBLR

0

0

5

10

15

STLM

0

0

21

142

218

OFM

-

0

0

9

70

CM

-

-

-

-

-

TABM

-

-

-

-

-

LPTB

-

-

-

-

-

Key to acronyms: RBLR - redbanded leafroller; STLM - spotted tentiform leafminer; OFM - Oriental fruit moth; CM – codling moth; TABM – tufted apple bud moth; LPTB – lesser peach tree borer

 

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 (April 28) mentioned in the table are based on the weather forecast. 

Biglerville

  3/31 

4/07 

4/14 

4/21 

4/28

2011

138

179

245

338

454

2010

194

334

412

486

562

2009

157

210

242

305

439

2008

137

178

255

355

472

2007

213

249

259

290

394

2006

194

258

338

447

514

2005

99

164

241

343

400

 

Rock Spring

 3/31

4/07 

 4/14

 4/21

 4/28

2011

78

96

147

203

293

2010

141

277

342

408

463

2009

116

156

173

226

349

2008

61

88

146

240

352

2007

147

189

192

218

300

2006

129

176

247

342

388

2005

52

92

172

264

298

Where trade names appear, no discrimination is intended, and no endorsement by Penn State Cooperative Extension is implied. Recommendations based on conditions observed at Penn State Fruit Research and Extension Center, Biglerville, PA.