During our scouting this morning we observed increasing injury from plum curculio and first flight of codling moth in pheromone baited traps. This signals a transition into the crux of the season for insect pest management.
So Long Bloom: When a pink application of an insecticide is used, we are often able to buy ourselves some time (10-14 days) to remove bees from mixed variety blocks during fruit set that provides some control of the insect pest complex during the early stage of petal fall. This is especially true in years of short bloom, when additional control is achieved from pink applications for San Jose scale, European apple sayfly (EAS), mullen plant bug (MPB), overwintering larva presence of obliquebanded leafroller (OBLR) and early migration of plum curculio into apple. This season however, we experienced extended bloom and late PC migration.
The Petal Fall (PF) insecticide, applied on or about the 12th of May this year in the mid-Hudson Valley, is now exhausted with the dilution of 1.24 inches of rain coupled with significant extension growth. We will require additional insecticide residue during 1st cover (this week) and likely a 2nd cover application to control plum curculio to maintain fruit quality until the 308 Degree Days are completed, signaling the end of PC oviposition (in most years).
Plum Curculio (PC): Very warm temperatures forecast for this week will provide ideal conditions for plum curculio migration and egg laying in developing tree fruit. On Thursday, 19th of May we found our first PC sting in unsprayed Jersey McIntosh fruit along the orchard border, almost a week after petal fall. As of this morning we are seeing 2% injury in Ginger Gold and 8% in Red Delicious in our unsprayed research plots.
Considering the extended bloom of most varieties driven by cool days and colder night temperatures, the pink applications appeared to have little impact in the way of residual efficacy for PC in late varieties this season. Low incidence of OBLR presence, slight injury from TPB and MPB, very low EAS combined with no early migration of PC this season was observed during the first week post petal fall. At the end of the day, save the management of San Jose scale (which is essential in many orchards) we could have gone without a pink insecticide this season.
Early varietal petal fall applications made last Thursday, May 12th, are now waning or spent. Cover applications with effective residual for PC will be critical during the next few weeks as populations continue to move into orchards in earnest now that warm temperatures have arrived.
The majority of eggs deposited into fruit by overwintering plum curculio in the Northeast is completed in apples once 308 DD base 50 from McIntosh 95% petal fall has been reached, developed in studies conducted by by W. H. Reissig, J.P. Nyrop, and R. Straub (Environmental Entomology; 1053-1060; 1998; have shown as per the “Oviposition Model for Timing Insecticide Applications Against Plum Curculio (Coleoptera: Curculionidae) in New York State”).
In most years control measures for PC are needed until 308 degree days have accumulated since petal fall. Insecticide residual will need to be effective until PC have completed emergence. Based on limited and unreliable weather patterns, the forecast date for the 308DD is approximately June 3rd. However, given the losses of fruit in abandoned trees as oviposition sites for PC, migration may continue further into the season in blocks with high historical populations.
In years when cool weather delay PC egg laying and frost reduce wild apple numbers, significant egg laying by PC can extend beyond this 308 DD point. In Michigan, researchers observed the reduced fruit crops in 1994, 2002, and 2008 was followed by prolonged PC injury to apple. Extending the coverage to 600 DD base 50 in apples in such years should be considered in sites where PC is a historical problem.
Weather Windows: Predicted winds will be increasing today, diminishing tomorrow into Tuesday. A 40% chance of showers are predicted tonight into tomorrow with light winds Tuesday evening into Wednesday morning.
Preserving the ‘King Fruit’: The king fruitlet is usually the first fruit ‘stung’ by PC. The king sizes up quickly relative to lateral set, and as such, is more vulnerable to PC injury. It is also the most valuable fruit as it is retained during crop load reduction efforts, likely to be the largest of the fruit in a cluster. However, this season we experienced significant variability of apple set due to bud freeze injury that occurred on April 5-6th with very high losses of the king flower this season. (19.1F Highland, 14.5F Marlboro Ridge, 8.4F Hudson, 9.8F Altamont, 11.6F in Clifton Park).
In unmanaged apple we find PC damage has already begun where adults have moved into orchards from the wooded edge. However, the next three days could bring significant injury where fruit size exceeds 5mm. We are seeing king of Ginger Gold at 14.5mm with lateral fruit averaging 8.5mm, Red Delicious kings at at 14.5mm with lateral fruit averaging 12.0mm. Management should begin at your earliest application window in ‘at risk’ blocks.
Applications using effective insecticides against plum curculio should control the pest for about 10-14 days based on materials and weathering. In selecting insecticides at this time be sure the materials are effective against codling moth, which is likely to hatch by early next week.
Frequent short interval rains will remove surface contact insecticide residual. Incidence of observed PC damage is highly variable among different orchards. PC damage often occurs in the same locations in orchards year after year, regardless of treatment levels with the potential for damage in any particular orchard fairly predictable from past observations.
Insecticides effective against the PC include Avaunt 30WDG (indoxacarb), the neonicotinoids; Actara 25WDG (thiamethoxam), the OP Imidan 70WP, WSP (Phosmet), carbamate; Sevin (carbaryl), and pyrethroids Danitol 2.4EC (fenpropathrin), Asana XL (esfenvalerate), Baythroid XL 1E, 2EC (beta-cyfluthrin), Lambda-Cy 1CS (lambda-cyhalothrin), Warrior 1CS (lambda-cyhalothrin), Proaxis 0.5CS, and pre-mix formulations Endigo ZC (lambda-cyhalothrin / thiamethoxam), Leverage 360 (imidacloprid / beta-cyfluthrin), Gladiator (zeta-cypermethrin / avermectin), Voliam Express (lambda-cyhalothrin / thiamethoxam), Voliam Flexi (chlorantraniliprol / thiamethoxam).
The pyrethroids and phosmet have broad spectrum activity to include PC, EAS, lepidopteran larva (OFM, CM, Lesser appleworm (LAW) and Obliquebanded leafroller (OBLR). They have no activity against rosy apple aphid (RAA) in curled foliage.
Imidan (phosmet), an organophosphate will also control most of the apple insect complex but is not translaminar and as such will not penetrate the leaf to control RAA or STLM. It will control the leafroller complex to a greater degree then Actara, which has very little value for internal lepidopteran such as codling moth or leafroller management.
Thus far the overwintering larval damage from Obliquebaned Leafroller (OBLR) has been low at the HVRL station but we are seeing increasing damage in the southern counties. For best control of OBLR a resistant management practice of alternating insecticide classes should be in place this season. Use of Intrepid 2F (IRAC Class 18) or Proclaim 5SG (IRAC Class 6) at petal fall for the overwintering population, followed by summer generation management using either (Altacor 35WDG or Belt 4SC), as these two insecticides are in the same IRAC class 28; OR Delegate 25WG (IRAC Class 5). In so doing we rotate insecticide classes for each of the two generations.
Codling Moth adults have been captured in Highland this morning, 23rd of May. Many insecticides used against the PC will manage the CM larva. However, Actara, a good PC material at the high-labeled rate, will have no efficacy against the CM larva, allowing larva to get a foothold in the orchard. In blocks where this insect has been problematic choosing insecticide with efficacy against PC and CM should be strongly considered (Rated as highly effective against both PC and CM: Imidan, Leverage, Voliam Flexi and Voliam Xpress). If additional applications for CM are needed after migration of PC is complete, the use of CM specific insecticides can be employed such as Altacor, Assail, Belt, Delegate, Lannate, and the pyrethroid group.
This insect is typically managed beginning at 1-2Cover. The first eggs hatch after about 220 DD, is predicted to occur 27 May. Insecticides that need to be present before egg laying such as (Rimon, applied at about 50-75 DD) are a good choice at this time given the adults have not yet laid eggs on the foliage or fruit. Insecticides that target the egg laying and hatch period should be applied at the next available window.
Use of pre-mix formulations containing multiple active ingredients (A.I.) should take into account the need for the A.I. during the remainder of the season so as to ‘need’ both A.I.’s and monitor usage within labeled seasonal amount restrictions. For example, if use use Voliam Flexi or Voliam Xpress, the A.I. chlorantraniliprole may prohibit the use of Altacor (A.I. chlorantraniliprole) later in the season for OBLR.
In the article “All in the mix”, Dr. Art Agnello points out that ‘the amount of chlorantraniliprole a.i. in a high-rate application of Voliam Xpress (0.078 lb) is lower than a comparable application of Altacor (0.099 lb); also, you can see the difference in thiamethoxam a.i. between the use rates of Endigo (0.046-0.055 lb) and Actara (0.070-0.086lb).
Additionally, note that thiamethoxam is limited to a maximum seasonal total of 0.172 lb/A, regardless of the formulation, which can complicate mixing & matching of products during the season.’ It’s very important to know that if a full rate of thiamethoxam is essential for plum curculio management in high pressure blocks, then a pre-mix may not be the best option.