Factors Contributing to the 2023 Hudson Valley Pome Fruit Season and Insect Pest Management Anomalies

Rainfall accumulations & temperature events:  Total accumulations for the growing season between March 1st and September 1st in Milton, NY was 27.16”, significantly higher than 2022 with 20.48”. The start of the 2023 season began relatively mild in March with higher-than-average rainfall up to April with rainfall accumulations of 4.62” in March (3.6” Ave.), yet well above average with 6.44” of rainfall in April (3.8” Ave.) causing orchard erosion leading to standing water and tree stress in low lying rows. Unseasonably high temperatures from the 11th to the 16th April ranged from 70.0oF to 91oF, increasing flower development from tight cluster to King Bloom in McIntosh by the 23rd April.

Cooling temperatures created a 14d lingering bloom with petal fall approximately on the 30th April. Average rainfall over the past 44 years in May is 4.43” with a near drought month and mild soil drying with 1.31” of rain this season.

June had below average rain events totaling 3.28”, yet enough to produce moderate levels of apple scab and fire blight infection in tree fruit blocks of sensitive varieties. Fruit set in early May had developed to 10mm. On May 18th a freeze event across the Northeast caused significant injury to developing fruitlets with losses exceeding 30%. June experienced moderate rain resulting in 3.2” (4.4” Ave.), followed by mild temperature, very dry early followed by intermittent rain during the latter weeks.

July experienced high levels of rain resulting in 6.84” (4.2” Ave.) with one day at or above 90oF, requiring no irrigation. Early apple scab in susceptible varieties produced high levels of secondary inoculum causing high mid-season infections.

August also experienced slightly higher than normal rainfall with accumulations of 4.67” (4.2” Ave.), providing large fruit beginning with early season fruit of Sweetango. Early Gala was challenged with prolonged bloom and fruit size variability. September also had significant rain events totaling 7.9” up to the 25th of the month.

The freeze event across the region on 18th May was followed by frequent hail events producing significant injury to developing pome fruitlets throughout much of the season. Most Peach, Apricot, Nectarine were lost with a light crop of Sweet Cherry remaining. Thinning was postponed for many growers during the mid-late May thinning window to evaluate crop and allow for damaged fruit to fall. Damaged fruit remaining on the tree was then chemically thinned and hand harvested to remove fruit expressing deformities, frost rings and later in the season to cull fruit with hail injury along with late expression of cold injury in most varieties.  Much of the fruit ‘out-grew’ the calex end deformities, such as Red Delicious and Gala, yet some damage did appear quite late and lingered with expanding fruit cracking adding to the cull.

At harvest fruit size was heavy, especially in the upper canopy, provided by ample season long rains. In tall spindle rows, crops could not be fully supported with 2’ x 4’ posts reinforcing top wire. Yet entire rows collapsed from uneven loads or down hill posturing, primarily in angled end post systems with a few H-Brace systems also succumbing to the weight. Many difficulties aside, mid and lower Hudson Valley orchard sites did provided growers with a near full harvest of many varieties. Unfortunately, Northern Hudson Valley and northeastern orchards did not fair as well.

Tree phenology: Moderating temperatures in late March supported the onset of bud development with green-tip on March 31st in HoneyCrisp, Snapdragon and Fuji in 30-75% of buds (the 43 year mean of 25th March in McIntosh).

Tight cluster followed on 11th April. 1st Bloom on 28th followed by cold temperatures. McIntosh had a 14-day bloom period to >80% PF, 5 days longer then the 9-day average.

Petal Fall (May 7th ) began the ‘growing season’ 4-days earlier than average to to a week of unseasonable warm weather, pre-disposing fruit to cold injury in mid-May. Fruit injury across varieties (below) was dramatic shortly after the event, with Macoun and McIntosh showing relatively low levels of injury, Jonagold with moderate levels, Snapdragon expressing severe russeting and Honeycrisp with very high degrees of longitudinal splitting and significant internal injury.

Degree-day accumulations of 449 43BE were below the mean mid-range of the 43-year average up to PF (506 43 BE), with lower high base temperature accumulations at 230 50BE in comparison to the mid-range.

A wide temperature range of 31.7oF to 77.1oF occurred during bloom (McIntosh: April 23-May 7), keeping bees from working flowers during the early bloom period, then followed by mild temps of mid-30’s to 85oF 10-days after PF.

Trees required targeted yet prudent thinning for a marketable crop with aggressive thinning made to Gala, Ruby Frost and Honey Crisp by hand given freeze injury. In hand and chemically thinned blocks retaining sound fruit, levels of the early-season crop varieties such as Sweetango, Ginger Goid, early Gala and Premiere Honey Crisp were harvested at optimum or above size grade. Frequent hail events occurred throughout pockets of Columbia County, southern Vermont and New England orchards causing severe loss of marketable fruit. At early harvest, relatively low soluble solid values and Brix, below 14, were harvested with good color by early August through early September. Later varieties were challenged by lack of color by overcast skies and intermittent rains. Low levels of bitter pit were observed at harvest in mid-late pick honey crisp with higher crop load and smaller fruit showing lower levels of BP.

Bitter pit was prevalent across most late season varieties at low to moderate levels, supported by applications of calcium. Hail events caused extremely high levels of injury in segments of the lower to mid-Hudson Valley this season.

San Jose Scale (SJS) was observed in individual trees infested in 2023 in both endemic populations over multiple seasons in cider apple blocks while isolated pockets in the center of blocks were found occurring in well managed orchards.

European Red Mite (ERM) :No overwintering eggs were observed in infested varieties the previous season, yet management was required by early August. By Late July Gala expressed individual tree ‘pockets’ of very high populations of European Red Mite (ERM) adults, found during weekly scouting in tree assessments, causing the onset of bronzing. Snapdragon was found with both ERM and Two Spotted Spider Mite (TSSM) the following week, followed by infested rows of HoneyCrisp, 100 meter away to leeward, suggesting mite ‘arrived’ from a different location.

Pheromone traps placed in Milton on the 12th of March captured the first seasonal Redbanded Leafroller (RBLR) Argyrotaenia velutinana (Walker) at 1/trap/wk on 17th March with 1st gen. peak flight on the 14th April at 55/trap/wk.

The overwintering larvae of the Speckled Green Fruit Worm (SGFW) Orthosia hibisci emerging as adults the week of the 24th March peaked on the 27th April at 50/trap/wk. Gypsy (now Spongy) moth were observed by late May.

The Black Stem Borer (BSB) Xylosandrus germanus (Blandford), an Ambrosia Beetle species, a sporadic pest of apple, caused significant tree loss in commercial orchards during the 2021-23 growing seasons. Fuji and Honey Crisp on dwarfing M9 rootstock in locations with well drained ripped shale outcroppings in Hudson Valley sites in Marlboro and Walden under drought conditions were found to contain BSB entry sites and rapid apple decline (RAD).

These sites were under irrigation both seasons yet proved insufficient during drought to maintain low levels of stress induced ETOH. Few sites with BSB induced RAD were observed in low lying situations with seasonal standing water. Invariably, young trees coming from nurseries appear to have insufficient root systems on M9 & often B9, to withstand extreme wet or dry soil conditions during the first few years after planting.

Dr Jason Londo has, in recent studies into apple rootstock winter hardiness, shown striking differences in cold temperature acclimation and deacclimation through the season*. The freeze events that then kill parts or all of the rootstockj then appear as dying cambium and bark, eventually separating from the trunk, allowing BSB and Dogwood Borer (DWB) to infest the trunk, causing tree decline.

Studies conducted at Rutgers University have shown Glufosinate-ammonium (Interline® Rely®) that can contribute to tree trunk injury under certain environmental conditions and subsequently cause tree decline and loss. Glyphosate may also play a role in tree decline.

Dr. Hannah Mathers, an independent nursery crop/landscape consultant with Mathers Environmental Services, LLC, conducted research on bark splitting of nursery and landscape trees during her time at The Ohio State University. She found that drift from late-season glyphosate applications was absorbed into young trees, damaging the bark structure and reducing their winter hardiness. This resulted in bark splitting that can open these trees to various pathogens. Mathers also found that formulations of glyphosate that contain surfactants (products that increase its absorption into target weeds) increase the likelihood of damage. Herbicide injury, drought and flooding may also be predisposing trees to stress leading to the production of EtOH and BSB infestation.

Tarnished Plant Bug (TPB) Lygus lineolaris presence in combination with other members of the plant bug complex including Mullein Plant Bug were observed at low numbers during the early season in managed trees, causing very low fruit injury levels, found to be well below the seasonal average. Orchards with historical fruit damage from TPB required timely applications for management in orchards shortly before and after petal fall. Injury occurred primarily during the pre bloom period this season as warm temperatures prior to bloom were conducive to TPB activity. Injury from this pest was observed to be at <0.5% by the 26th  of May in the UTC varieties this season with small smooth raised protuberances (MPB) and more typical inverted punctures (TPB) found on sampled fruit. Observed TPB injury during harvest fruit evaluations in Ginger Gold in 7th September in untreated plot ranged between 1.0-5.0.0%.

Plum Curculio (PC) Conotrachelus nenuphar damage levels were moderate to severe this season with 28% ovipositional injury assessed on 2nd June in Macoun. Ovipositional injury occurred during the two weeks following petal fall (14th May).

First observation of PC presence and damaged fruitlets was the 21st May (<1%). Macoun, the variety used in efficacy screening studies, had exceeded 8 mm in diameter by 21st May, at which time 5.0% was observed at 7 days post PF. PC ovipositional injury to fruit remained moderate to severe in UTC trees into the season expressing 18-60% injury, which was separated into two categories, which included early oviposition scaring and late season feeding injury by PC up to harvest.

European apple sawfly (EAS) Hoplocampa testudinea (Klug) activity occurred in very low numbers again this season with early varieties showing a range from 0.0% to 0.2% injury in Macoun cluster fruit evaluations with early harvest assessments at < 0.1%. This was the seventh year in which EAS populations were at very low fruit damage levels.

Spotted Tentiform Leafminer (STLM) Phyllonorycter blancardella adult populations remain at very high levels in seasonal pheromone trapping showing two distinct flights. Since the planting of semi-dwarf trees that correlate with the onset and use of the neonicotinoid class of insecticides employed in apple along with the reduced use of broad spectrum OP use leading to parasitic biological  control of the larval stage, the STLM has not been observed to cause injury to foliage to a degree requiring insecticide management. Seasonal parasitism of early larval stages continues to be observed in trees with ‘soft’ insecticide programs.

San Jose scale (SJS) crawler emergence of 1st generation was predicted to occur during the second week of June (10th – 14th June), biofix based on the 1st adult pheromone capture on 21 May and using a 260-360 DD50BE model. Second generation was predicted based on second flight occurring 16 July. In general, SJS scale levels were low in infested trees. The infestation means ranged from 0.3% to 25.0% injury observed research plots on 19th August representing combined 1st and 2nd generation fruit infestation levels. In conventionally treated orchards, the SJS has become a major insect pest to manage in apple, requiring targeted applications for multiple generations. In recent years we’ve observed a 3rd generation in late September.

The Lepidopteran complex: Overwintering larvae of the spotted green fruit worm (SGFW), obliquebanded leafroller (OBLR), and newly emerging adults of the red banded leafroller (RBLR) during the pre-bloom period through fruit set remain a concern for most Hudson Valley and Lake Champlain pome fruit growers. The tools for use against the lepidoptera complex are diverse in mode of action, effective, and have excellent residual activity. Growers tend to lean heavily now on the use of the highly effective Diamide and Spinosyn groups for Lep. Management. Mid-late season leafroller damage levels of infestation were observed in harvest ratings for ranging between 3.0-30.0% injury at harvest of Macoun in mid- August.

Codling Moth (CM) 1st generation sustained adult flight occurred on 21st May with first hatch / larval emergence predicted for 2nd June using 220 DD50BE from CM biofix. Complete hatch of 1st generation was predicted by 1st July. Frass from CM observed on  July at. The internal lepidopteran complex, lesser apple worm (LAW), oriental fruit moth (OFM), and codling moth (CM), showed relatively high levels of damage to apple, with frass produced by the internal lepidopteran complex appearing during mid-late July. The 2nd generation adult emergence followed by sustained catch for the CM biofix occurred on 20th of July with management for larval emergence prediction using 250 DD50BE to occur on July 31st. Damage from 1st and 2nd generation CM evaluated at harvest on Macoun showed 24.0% injured fruit in screening trials of most infested treatment.

Obliquebanded leafroller (OBLR) monitoring and management by tree fruit growers continues to be a high priority, albeit significantly lower levels of fruit injury is attributed to the leafroller complex in fruit pack-out assessments. By targeting up to three seasonal application windows while employing a single mode of action for each management window, growers can achieve successful management of OBLR larvae. Recommended application windows include the pre-bloom through petal fall period for the overwintering generation, often using Bt during bloom, IGR’s such as Proclaim and Intrepid at petal fall, the summer generation using either Harvanta, Altacor or Delegate, and later in August applying either Delegate or Altacor in rotation for resistance management. Recommendations for applications were made using insect phenology predictions for early emergence, using 340 DD50BE from biofix to manage emergence of larvae, predicted to occur on mid-June. In general, low levels of leafroller feeding were observed on developing foliage and fruitlets in spring 2023. Trap captures began on 2nd June and were low to moderate for 1st generation OBLR. The 340 DD43BE emergence date of 1st summer OBLR generation was 16th June. The 2nd generation flight began on the 27nd of July with larval emergence predicted for the 16th of August. OBLR trap numbers were very low during August at 2.4 adults per day.

Apple maggot (AM) 1st adult capture on 8th July from abandoned orchard in Milton, NY was very late this season compared with first emergence on 22th June in 2021. Drought created poor conditions for adult emergence due to hard pack soils in commercial blocks and as such, threshold of 5 flies per trap per block was not observed in commercial orchards this season in most commercial managed orchards. Injury in treated and untreated trees in our research block however had a range of 10-29% tunneling from AM.

The brown marmorated stink bug (BMSB), Halyomorpha halys, has been observed throughout the southern Hudson Valley for the past 14 years with the first BMSB confirmation in NYS on December 2008. Since that time, increasing populations have been documented in urban environments then becoming an economic pest on farms throughout the lower to mid-Hudson Valley region and most recently along the Lake Ontario fruit growing region.

We have observed a second generation over the past few years, developing in mid-late August from research based voltinism studies. In 2021 we again found oviposition and newly emerging nymphs from mid-August through September. There appears to be high levels of stink bug feeding in apple this season from both BMSB and the green stink bug, Acrosternum hilare. Both species being arboreal insects, they have been found from mid-season through harvest on pome fruit in lower to mid-Hudson Valley with increasing northern observations and fruit injury of BMSB observed in traps and higher incidence of fruit injury in WNY along the Lake Ontario fruit growing region.

Nymph and adult trap captures of BMSB using Tedders traps employing the USDA #10 lure, and the Plaudi stali aggregation pheromone lure, methyl (E,E,Z)-2,4,6-decatrienoate, were observed along orchard edges in 2022, and as such, we employ a trap threshold of 10 total BMSB adults per trap per week to recommend management timing for tree fruit production.

*Winter injury continues to occur in well managed apple orchards and contributes to trunk injury and stress, causing the tree to produce EtOH which, acts as a trigger for BSB infestation.

Studies from the CALS lab of Jason Londo suggest M.9 is the least cold hardy of the rootstock series studied, while G.41 retained its deep cold hardiness throughout the sampled months (Nov.-Jan). In this study, deacclimation was evident for G.222, G.890, and G.935, which all lost substantial hardiness between December and January, which can lead to injury during a late season freeze event.

Apple trees can also experience rootstock and scion injury in compromised soil conditions in the Hudson Valley. Injury is often but not exclusively found trees growing in low-lying sites, hillside depressions, sunken tree rows or shale ‘dry’ soils where water accumulates and is retained for extended periods.

‘Drought’ conditions from lack of water holding soil such as alluvial and shale soils can also cause significant tree stress.

Temperatures during the winter of 2023-24 led to tree decline with injury noted as splitting and separation of bark from the trunk. This further resulted in the loss of live cambium leading to subsequent tree death as fruit growth requirements impose excessive tree stress due to inadequate water movement capacity.

Winter injury of trees have been observed to succumb to BSB infestation.

Additionally, as mentioned above under Black Stem Borer, herbicides may also play an important role in the yearly and seasonal repetitive application. Conditions leading to chemical penetration into the bark to cause injury to the cambium, such as industry formulation change or the addition of adjuvants may increase the likelihood of trunk injury.