To provide Asian pear growers with more sustainable, cost-effective thinning strategies, a SARE-funded team of researchers and farmers studied how effectively Asian pears were thinned by benzyladenine. They found that MaxCel, one of several chemical thinners that contain benzyladenine, can reduce the cost of hand-thinning by up to 50 percent while delivering fruit yields and sizes comparable to those of untreated, hand-thinned control trees. Rutgers University has produced a fact sheet that provides a brief introduction to plant growth regulators and directions on how to use MaxCel as a crop thinner for Asian pears.
Codling moth egg hatch is at about 10 percent and Oriental fruit moth egg hatch is at almost 100 percent. The flights of obliquebanded leafroller (OBLR) and peach tree borer (PTB) are expected to start within the next few days. Green peach aphid (GPA) (on stone fruit) and spirea aphid (SA) (on stone and pome fruit) colonies are being observed in some orchards. Watch for predator populations such as ladybird beetles or syrphid fly larvae.
The rain occurring today could have the potential to produce an apple scab infection event if adequate leaf wetness hours are achieved. Growers are encouraged to monitor conditions in their orchards and spray accordingly to protect for apple scab. In addition, be mindful of rust: the cedar galls have made their appearance, making spores available to cause infection in apple trees.
Temperatures will gradually increase to more seasonable weather beginning Monday. Bright sunny days with seasonable temperatures will mean it will be harder to remove fruits.
If the rain in the forecast comes to fruition this weekend, be prepared for a major apple scab infection period for the region. Growers in northern PA still in bloom need to be vigilant for fire blight conditions this weekend and next week. Although many are past bloom in the region, we experienced fire blight conditions from May 5 – May 12 and growers should begin to scout for infections during the coming week. Be on alert for powdery mildew infections, thanks to the dry weather lately. Control measures are needed to manage bacterial spot on stone fruit.
As the first insecticide application after petal fall should already be completed in most orchards, it is time to plan for the early summer control of other insect pests.
The MaluSim Carbohydrate model was run the morning of May 15 for 11 sites across the state. Results for May 15 through May 18 are predicted data based on weather forecasts.
Generally only a sporadic minor pest, green fruitworm is showing up in orchards across the state in much higher numbers than ever seen before.
All except the two farthest north stations have reported full bloom. This past weekend temperatures shortened bloom as most sites are either past petal fall or into petal fall.
Stations in central PA and northern PA have not yet reached full bloom. We anticipate full bloom in Centre county for tomorrow and will be applying a thinner application of Amid-Thin to a block of Honeycrisp as a research trial.
Appropriate, effective insecticides should be applied based on orchard monitoring and documented pest control needs. On apples, the after petal fall insecticide application represents the best timing to control plum curculio and European apple sawfly. The petal fall timing on apples will also be a good time to control Oriental fruit moth, obliquebanded leafroller, mites and aphids.
Full bloom came on extremely rapidly across the state over the past few days. Prior to this weekend most areas of the state were a little behind the normal timing of flower development. However, the warm temperatures of the weekend across the entire state pushed flower development.
A weather system moving East will be bringing rain Tuesday into Wednesday. At the same time we are experiencing the peak period for dispersal of mature scab spores. The predictive models indicate May 5 - 6, 2015 will be a scab infection period. Growers need to protect trees to prevent scab infection during this critical period.
Brown marmorated stink bug adults are slowly emerging from their overwintering shelters. The five percent egg hatch of Oriental fruit moth (and the optimal timing to start controlling OFM) is expected around May 7th in the Biglerville area. All pheromone traps for monitoring fruit pests except traps for obliquebanded leafroller (OBLR) and peach tree borer (PTB) should already be placed in orchards.
All predictive models indicate a high risk for fire blight infection this week due to the high temperature, humidity, and chance of rain showers in the forecast. Growers should begin protecting blossoms with streptomycin on Monday. More strep applications will be needed as infection conditions persist.
Growers are reporting that some blocks of young trees have a heavy bloom and are concerned about negative effects on the vegetative growth of the trees in these early establishment years.
Preliminary trials with Amid-Thin (NAD) indicate it may be a useful thinning tool on Honeycrisp and Pink Lady at bloom and/or petal fall. Growers are cautioned to not spray pigmy-prone cultivars and not to spray past petal fall, as there is an increased risk of inducing small fruit to stick at later timings. Conduct your own trials with this product – including unsprayed checks – prior to deciding whether this is a good thinning tool for you.
Recently a grower mentioned he was having trouble controlling Wild Carrot, Queen Ann’s Lace, Bird’s Nest, Bishop’s Lace. In case you did not know, all the individual common names mentioned are the same plant - Daucus carota. Wild carrot is a biennial weed, as its life cycle requires two years to complete.
Rain is in the forecast for Thursday and Friday. As a result, the prediction models indicate this will be a scab infection period -- and a big one since we’re reaching peak maturity with spore release. This weather will also be ideal for cedar apple rust infection. Growers are encouraged to have trees protected before the rain occurs. In addition, growers need to be on alert for next week since fire blight models indicate the week of May 4 may be an infection period.
The Tree Fruit Production website has been upgraded for the new growing season and we hope you'll find many of the new features useful. You can more easily access seasonal monitoring data, and pest management and plant growth regulator recommendation tables have been added.