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Insect Pest Observations in Hudson Valley Apple Orchards. April 30th, 2018

Scouting, Trap Captures and Management

Our 2018 scouting report is now available through our blog site providing weekly updates of insect observations, pheromone trap captures, forecast emergence of damaging life stages and early season tree fruit phenology.

Warm weather will drive leaf expansion and fruit bud development over the next 5-days. Temperatures will climb into the 70’s with tight cluster expected by 2nd of May and 80’s later in the week with early varieties such as Ginger Gold in full pink by weeks end.

Observations:

1st instar psylla nymph

Pears:
*Pears are moving through late Bud Burst into Green Cluster stage. The first emergence of the first pear psylla nymphs occurred early last week. In untreated pear, egg laying has increased to 1.8 eggs per bud while nymphs are hatching and observed at 1 nymph/25 buds.

Apple:
*Early apple varieties are moving into Pink. Flight of green fruitworm, redbanded leafroller, lesser appleworm and spotted tentiform leafminer. The first larva to emerge will be the complex of green fruitworm followed by obliquebanded leafroller larva. Forecast high temperatures this week will provide ideal conditions for larval emergence. Larval stages of these insects will begin feeding on new foliage and fruit buds over the next two weeks as we move into bloom in early to mid-May. Scout for leaf and bud feeding on flower clusters to determine the extent of feeding for management. Check 10 shoot tips and fruit clusters per tree for leafroller larvae in webbed leaves and for surface feeding damage on clusters using 3-4% feeding as the threshold in most varieties, lower in high valued varieties.

*Tarnish Plant Bug (TPB) In apple blocks near unmanaged broad leaf weeds scout for adults on flowers and foliage looking closely for bleeding wounds on shoots and flower buds. This will occur as temperatures move into the 80’s.

*Rosy Apple Aphid (RAA) will be emerging through pink to begin feeding on terminal stems, cluster leaves and fruit clusters. This is the most damaging aphid species when present on apple. Rosy apple aphids cluster on leaves of fruit spurs and growing shoots where they cause severe leaf curling with infested fruit spurs underdeveloped and misshapen as the season progresses.

*Black Stem Borer (BSB) Xylosandrus germanus, is a devastating pest of young apple trees in our region. Early spring activity (!st week in May), during female emergence and migration to apple under stress have had serious consequences for tree health. Infested trees will decline rapidly and often die within the 1st-2nd year of infestation. In 2015 trapping for this pest found the insect in 11 Hudson Valley and 9 Champlain Valley orchards. Scout for toothpick frass on the trunk of young trees. A single site should prompt trunk applications.

*San Jose scale (SJS) is often a problem in large, older trees good spray coverage is often difficult to achieve during the onset of 2nd generation late in summer. However, given the shift in material usage, younger high density blocks are also vulnerable. SJS will injects toxin into the tree as it feeds causing localized discoloration to the limb, red blemishes on fruit and left uncontrolled, San Jose scale can kill the tree over the next few years. Scout for adult scale on limbs and shoots in the 2nd year and older. Carve into infested limbs to confirm the reddish cambium and xylem wood beneath the bark. Place black electrical tape around infested limbs at (300DD base 50F), approximately late May, can be set to monitor crawler activity in June for the use of contact insecticides. Pheromone traps can also be used along with degree-day modeling to predict crawler emergence.

*Dogwood borer Syanthedon scitula (Harris) is a continuing problem in the Hudson Valley. This insect is in the family of clearwing moths bearing a close resemblance to wasps. Malling and Malling-Merton rootstocks (M-9, MM#), which are much more prone to produce burr knots or rooting initials, are highly susceptible to DWB infestations as the females often deposit eggs in burr knots. Larvae feed in the burr knots into which they hatch, and they mine beneath the bark to feed. The feeding of larvae on the cambial tissue beneath the bark inflicts damage to the tree and can cause tree decline and death. Scouting for fresh frass and larva is critical for the management of trees on dwarfing rootstock, especially varieties grafted to M-9 & G-11.

Pear Management Options at Green Cluster

Pear Management: Management for fabraea, pear psylla eggs and nymphs should be in progress. Pear midge should be managed prior to bloom to reduce leaf curl.

Continue oil and or Surround WP applications to reduce egg laying.
A Pyrethroid application used during cool evening or early morning temperatures may reduce adult populations. Yet widespread resistance of pear psylla to the pyrethroid class has occurred over the past 20 years of use.

Apple Management:
San Jose scale (SJS): Before the season takes you by storm, you should strongly consider managing SJS if you have had even the slightest amount of SJS scale in your orchard at packout in 2017. The recent post “San Jose Management: Scaling it Up as Buds Break” includes recommendations on SJS management. It’s not to late for a 1% horticultural oil application. However, the use of Captan prior to or post application of oils may cause a phytotoxic response to foliage or fruit. Lorsban foliar application plus 0.25%-1.0% horticultural oil (with no Captan residue) during delayed dormant to pink in combination with oil or alone is still effective, although some growers have seen diminishing levels of control in some blocks.

Rosy Apple Aphid (RAA). Lorsban foliar application plus 0.25%-1.0% horticultural oil (with no Captan residue) during delayed dormant to pink in combination with oil or alone is effective during the SJS application timing closer to pink. The neonicotinoid class including acetamiprid (Assail), thiamethoxam (Actara) and Imidacloprid (Admire Pro) have translaminar activity to effectively manage this pest. Best timing for the neonic’s would be at petal fall with post bloom applications for spirotetramat (Movento).

Pre-Bloom Apple Management Options

Dogwood borer (DWB) Hudson Valley orchards vary in degrees of insect presence relative to last years DWB management. Dogwood borer is both an established insect within the orchard and a migrating pest moving into the orchard each year. If you’ve cleaned up your orchard last season, consider mating disruption for DWB to maintain low levels of the borer or using Lorsban trunk applications in a maintenance program, especially where injury occurred over the past few years as endemic populations are difficult to eradicate.

Proximity to woodland and abandoned orchard, levels of reduced insecticide susceptibility, tree fruit varieties more or less prone to insect preference and a host of factors related to new invasive insects, weather, seasonality (and the list goes on) all play a roll in challenging successful pest management this season.