Although brown marmorated stink bug (BMSB) adults still continue to emerge from their overwintering shelters, this past week we observed the first BMSB eggs deposited on fruit trees. First generation codling moth (CM) flight is underway in apple and pear orchards.
Central PA experienced a cloudless sunny weekend and the fruit grew fast. Most sites in the report show a minor deficit of carbohydrate balance which should aid in removing fruit.
Most orchard sites are calling for a surplus of carbohydrate production through the weekend as temperatures become more seasonable and sunshine is predicted across the state.
Apple thinning carbohydrate models from around the state show a negative daily balance for today and tomorrow but in general the 4 day average balance is positive.
Weather conditions affect an apple tree’s response to chemical thinners. The Cornell Carbohydrate Model is an attempt to factor in the interaction of environmental conditions and a tree’s physiological status. The model utilizes temperature, solar radiation and day length based upon site-specific ground based measurements from a weather station in a grower's orchard block.
If adult stink bugs are observed in stone fruit orchards, a special BMSB directed treatment may be warranted. If hand applied mating disruption (MD) materials (Isomate products) are planned for the control of dogwood borer and/or peach tree borer or lesser peach tree borer, now is the latest time to place dispensers in orchards.
Storms occurring on May 22, 2014 in the eastern part of Pennsylvania produced hail, which was capable of causing damage to fruit trees. Growers in affected areas will want to consider applying a streptomycin spray within 24 hrs of the hail event to protect trees from fire blight.
The latest apple thinning carbohydrate models for fruit growing regions across the state have been posted at the Penn State Fruit Research and Extension Center website - http://agsci.psu.edu/frec/growing-season-information. For the coming four day predictions, most sites are calling for standard chemical thinner rates the first day, May 20, and increasing rates by 30% the next three days due to less demand for carbohydrates. If the spur leaves in an orchard block exhibit cold damage, however, you will need to adjust your thinning rates to account for potentially lower carbohydrate production.
The weather during May 2014 has provided excellent conditions favorable for disease. Disease control recommendations are covered for fire blight, apple scab, powdery mildew, rust, and bacterial spot on stone fruit. This is an updated version of the Disease Update posted on May 14, 2014.
2014 season weekly average captures of adult moths in pheromone traps and accumulated degree-days base 43°F.
The after petal fall treatment on apples is the best time to control plum curculio and European apple sawfly. During the 2014 season, the after petal fall insecticide treatment on apples (and shuck split on peaches) should also be effective in controlling Oriental fruit moth.
Weather conditions affect an apple tree’s response to chemical thinners. The Cornell Carbohydrate model is an attempt to factor in the interaction of environmental conditions and a tree’s physiological status. The model utilizes temperature, solar radiation and day length based upon site-specific ground based measurements from a weather station in a grower's orchard.
Fire blight risk remains high through the week. When applying streptomycin, it is effective for 24 hrs before and 24 hrs after a rain event. Apple scab spore dispersal is peaking, and with the predicted rain events this week, we are in for a very rough, serious infection period. There is potential for secondary spread if fungicide protection earlier this year was less than adequate. The humid conditions are also optimal for mildew and rust infections.
Clopyralid is a selective, post-emergence herbicide that has been labeled in stone fruits for many years. The addition of a supplemental labeling for apples (Stinger https://tinyurl.com/k7me49m ) will allow growers to control several important problem weeds. Right now, prior to bud stage, in mid-May, is especially good timing for Canada thistle control with clopyralid.
In the majority of orchards no stink bug control activities are required at this time. It is time to start more intensive insect pest management activities in peach orchards. The petal fall treatment on peaches should focus on controlling Oriental fruit moth and plum curculio. Pheromone traps for monitoring spotted tentiform leaf miner, Oriental fruit moth, redbanded leafroller, European apple sawfly, codling moth, tufted apple budmoth and lesser peach tree borer should already be placed in orchards.
The apple blossoms are open and conditions are soon to be optimal for fire blight infection. Keep an eye on the weather for favorable temperatures and moisture since forecasts indicate May 9th to 12th (and possibly beyond) to be an infection period. Blossoms need to be protected.
Brown marmorated stink bug (BMSB) started emerging from overwintering shelters. In the majority of orchards no stink bug control activities are required at this time. If hand applied mating disruption materials are planned for the control of codling moth, Oriental fruit moth, dogwood borer, peach tree borer or lesser peach tree borer, now is a time to place dispensers in orchards.
Recently, there has been a lot of press related to pollinator health, and some troubling information indicates that certain fungicides, when used during bloom, can negatively affect the health of honey bees. This is a complicated problem with the solutions relying on understanding the detailed relationships among chemicals, pollinators and pest management needs. It is not prudent to treat this topic with a broad brush with statements such as "All neonicotinoid insecticides are bad for all pollinator species," or "No fungicides should be sprayed during bloom." Research is on-going, and we do not know all of the details yet.
Apple scab spores continue to rapidly mature and be released. With the expected rainfall accumulations predicted for tonight to Wednesday night to be at least three inches, the stage could be set for a severe apple scab infection period. Growers are encouraged to apply a spray prior to rainfall, particularly to susceptible cultivars and areas known for high scab inoculum.
Early season apple disease management is primarily directed at controlling scab. At 39°F, 28 hours of continuous wetting are required for infection, while at 61 to 75°F, only 6 hours are required. The Revised Mills Table in this article will help you calculate apple scab infection periods.