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Pink: Spray or Not to Spray (TPB)

TPB injury to Gala.  Hudson, NY 2008

TPB injury to Gala.
Hudson, NY 2008

The most effective period of the season to control San Jose scale is during the pre-bloom period. Less foliage provides the best opportunity for greater application coverage to the limbs and trunk. Your 2014 harvest pack out data will be the indicator for SJS presence in the orchard (location) and % damage from SJS culls. Multiple approaches for SJS will be needed if multiple blocks suffered injury successive years. (See “Dogwood Borer and Scale: Not to be taken lightly”)

This insects aside, is there a need to make insecticide applications to your pome fruit during pink in Eastern NY?

During tight cluster through pink insects begin to emerge from overwintering sites. They overwinter in, or make their way to tree fruit orchards beginning at tight cluster. As each orchard may have dramatically different insect pest pressure during the pre-petal fall period, your orchard should be assessed at pink to determine the need for insect management prior to bloom.

Some factors that play into pre-bloom management decision making:
I. Insects species in your orchard that will or have caused injury to developing flowers and fruitlets
II. Bees: native or commercial honeybee hives and the bee keeper contract constraints
III. Timely honey bee hive removal
IV. Successful pollination and preservation of the king fruit during bloom

Pre-Bloom Insect Species Causing Injury to Developing Flowers and Fruitlets:
Tarnished Plant Bug, Lygus lineolaris (TPB). The insect infests over half of the cultivated plant species grown in the United States. It has piercing-sucking mouthparts and is a serious pest of fruit and vegetable in the Eastern US. Tarnished plant bug overwinters in the adult stage under leaf litter, stone walls, tree bark and other protected places along the edge of orchards. At the end of April, the adults become active and begin laying eggs in crop and weed hosts. The overwintering adult population peaks at about the pink stage of apple (early May in New York State).

Tarnished plant bug overwinters in the adult stage.

Tarnished plant bug overwinters in the adult stage.

Adults are 0.25 in. long, oval, and somewhat flattened. They are greenish brown in color, with reddish brown markings on the wings. A distinguishing characteristic is a small but distinct yellow-tipped triangle in the center of the back, behind the head.

Tarnished plant bug will move to buds and developing clusters as temperatures increase, moving back to suitable ground cover as temperatures fall. Maintaining the area beneath tree canopies ‘weed-free’ and the fescue-based sod in alleyways mowed will prevent buildup of flowering plants and reduce TPB activity.

The tarnished plant bug causes injury to tree fruits when it feeds and lays eggs. Damage occurs primarily in the spring on flower buds, blossoms, and young fruit, although bleeding of sap may result from twig and shoot injury. On apple trees, some early egg laying may take place in the buds. However, most eggs are laid in the developing fruit starting at bloom.

TPB Nymph

TPB Nymph

The insect begins feeding first on buds and later on developing fruit. Small droplets of sap may be present on the surface of injured buds. Within 1 or 2 weeks after feeding, the flower clusters may appear dried and the leaves distorted, with a distinct hole where the insect fed.

Generally, later damage to developing fruit is more important than earlier feeding on flower buds. In apples, feeding can cause punctures or deep dimples to form as the fruit develops, and in peaches various deformities known as “catfacing” occur.

The damage to apples caused by egg-laying is usually deeper, resulting in more distorted fruit often with blemishes or “scabs”. Damage early in the season tends to be near the calyx end of the fruit, and later injuries tend to be elsewhere. Cultivars differ in their susceptibility to damage, with depressions or scabs in some being less pronounced. Location of tree fruit near broad-leaf weed hosts edges of ponds or hedge rows also influences the likelihood of injury from TPB.

The use of unbaited, nonreflective, white sticky boards hung low in the trees to effectively monitor TPB can help in determining TPB activity. The best places to set the traps are in lower areas such as ditch banks and in hedgerows, which are favorable overwintering sites of the adults. White sticky traps are available commercially.

Peristenus digoneutis Loan (Hymenoptera: Braconidae)

Peristenus digoneutis Loan
(Hymenoptera: Braconidae)

A biological control parasite introduced into the Northeast from Europe that has been attributed to reduced TPB populations in both apple and alfalfa. This wasp parasite of the TPB, Peristenus digoneutis (hymenoptera: braconidae) is believed to have reduced both damage and occurrence of the TPB.

TPB Management:
• If your pack-out has greater than 4% culls from TPB an application is warranted.
• In varieties such as Honey Crisp in high density systems, lower injury levels may equate to economic injury.
• Target for application: sustained temp. >70 for three days or more beginning at TC.
• Applications at both TC and Pink were found most effective in years when TPB feeding is early and high.
• Pyrethroids have been shown to be very effective against TPB during the pre-bloom period.
• Neo-nicotinoid insecticide use at pre-bloom is less effective, and may NOT be acceptable to bee keepers.
• In years where the king fruit sets & grows, followed by cooler delayed bloom, it becomes susceptible to plum curculio injury. A pink pyrethroid will protect fruit by reducing early PC migrations during late pink and early bloom.
• In years when bee keepers are delayed in hive removal, pink applications will reduce European sawfly and plum curculio injury to sizing fruit.

Efficacy of Pyrethroid at TC and Pink. 2008

Efficacy of Pyrethroid at TC and Pink. 2008

So, to answer the question “to spray or not to spray at pink’ for TPB. If economic injury has been observed in the past few years in high valued fruit that exceeds the cost of the applications per block then treatment is warranted.

Important to note: The mite, Typhlodromus pyri, is a very effective predator, shown to manage European red mites (ERM), Panonychus ulmi. ERM feed on leaves of apple trees and interfere with photosynthesis and production of carbohydrates, reducing yield, fruit color, overall quality and subsequent fruit bud development. The use of pyrethroids and multiple applications of Manzate dramatically reduce or eliminate T. pyri populations. Reduced predation can contributes to mite flare-ups during the growing season.

Achieving Biological Control of European Red Mite in Northeast Apples: An Implementation Guide for Growers