Plum Curculio Damage on Cherry & Pear Increasing

Very warm temperatures we’ve experienced recently have provided conditions for stink bug migration to orchards and plum curculio egg laying in developing tree fruit (See Scouting Report).

Green stink bug feeding in sweet cherry.
Green stink bug feeding in sweet cherry.
The green stink bug, Chinavia halaris (Say), is a common insect pest of seeds, grain, nuts and fruit in North America. This species is has many host plants upon which it feeds. Drawing sap from fruit cells causes cell death that leads to flesh corking, ‘cat facing (in stone fruit) and dark sunken lesions in pears and apple resulting in unmarketable fruit. The stink bug is capable of traveling long distances to find food and are often seen aggregating in host plants. Drought conditions in the Hudson Valley have prompted stink bug to move from woodland to orchards with green stink bug feeding on sweet cherry fruit observed this morning. We have also seen increasing numbers of brown marmorated stink bug in pheromone trap captures in upper and mid-Hudson Valley orchards, yet below the action threshold of 10 adults / trap.

Insecticides effective at managing the stink bug complex include pyrethroids, in particular Danitol (fenpropathrin), and the pyrethroid-neonicotinoid combination of Endigo ZC (Thiamethoxam / lambda-cyhalothrin). These insecticides would also manage the apple insect pest complex including plum curculio at this time used using a high labeled rate.

Plum Curculio (PC): If a pink application of Lorsban, Calypso, or pyrethroids were used at high labeled rates you have bought yourself some time (10-14 days) to manage the insect pest complex at petal fall. Plum curculio migration, mating and egg laying occurred over the weekend with damage observed in apple, sweet cherry and pear this morning. Warm temperatures are predicted to diminish this week, BUT before we see cooler temps its likely that the next two days of mid-80F highs will provide ideal conditions for significant injury to occur from plum curculio from Hudson (Columbia County) to the lower mid-Hudson Valley tree fruit growing region. Most vulnerable today and tomorrow are the apricots, early cherry, Asian and European pear other early stone fruit and early apple such as Jersey Mac and Ginger Gold. Again, if pink insecticides were used (that manage PC) then you can delay until later in the week.

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.

In unmanaged trees, PC damage has already begun along the orchard edge where adults have moved into orchards from the wooded edge. However, the next three days could bring significant injury where fruit size exceeds 5mm. To date we have seen less then 1% injury in early varieties as of this morning. Management should begin at your earliest application window in ‘at risk’ blocks.

Predicted winds will be increasing today and tomorrow from the south then Tuesday night from the North to bring cooler temps for two days. A 30% chance of showers are predicted tonight into tomorrow (forecast).

The plum curculio.
The plum curculio.
Control measures 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 20th.

Applications using effective insecticides against plum curculio should control the pest for about 10-14 days based on materials and weathering.

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), Calypso 4F (thiacloprid), 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).

PC feeding damage at petal fall.
PC feeding damage at petal fall.
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.

Calypso 4F has activity against PC, EAS, RAA, leafhopper and leafminer, internal lepidopteran (OFM, LAW and CM) but only moderate to low activity against the OBLR.

Calypso 4F is slated for removal from our tree frtui toolbox. This is a very effective insecticide against PC, European apple sawfly, mullein plant bug, rosy apple aphid (RAA) and spotted tentiform leafminer (STML), may still be available and in stock this season. It has very low toxicity against honey bees, yet not very effective the stink bug and leaf roller complex. This will be the last year for use of Calypso 4F, one of the better OP replacement materials for PC management.

Plum curculio damage in early sweet cherry
Plum curculio damage in early sweet cherry

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 Calypso.

Thus far the overwintering larval damage from Obliquebaned Leafroller (OBLR) has been modest at the HVRL station but we are seeing increasing damage over the past 4 days. 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.

Plum curculio damage to Asian pear.
Plum curculio damage to Asian pear.

Codling Moth adults have been captured in Highland this morning, 11th 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: Calypso, 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 not a good choice at this time given the number of eggs already on the foliage. Insecticides that target the egg laying and hatch period should be applied at the next available window.

Plum curculio damage in Bartlett pear.
Plum curculio damage in Bartlett pear.

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.

If a pink application of Lorsban, Calypso, or pyrethroids were used at high labeled rates you have bought yourself some time (10-14 days) to manage the insect pest complex at petal fall.

If not, it might be wise to call your bee keeper, ask if he can screen the bees within the hive until they can be removed at a later date, and begin insect pest management in tree fruit over the next 24 hours, especially along the boarders. Managing PC should be a priority tonight and tomorrow morning to reduce losses from curculio this season.  for 11AM, 11 May
for 11AM, 11 May

About Peter J Jentsch

Peter J. Jentsch serves the mid-Hudson Valley pome fruit, grape and vegetable growers as the Senior Extension Associate in the Department of Entomology for Cornell University’s Hudson Valley Laboratory located in Highland, NY. He provides regional farmers with information on insect related research conducted on the laboratory’s 20-acre research farm for use in commercial and organic fruit and vegetable production. Peter is a graduate of the University of Nebraska with a Masters degree in Entomology. He is presently focusing on invasive insect species, monitoring in the urban environment and commercial agricultural production systems throughout the state
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