Fruit Times
This past winter at some of the fruit schools, I talked about the need to determine the nutrient status of your orchards through leaf analysis. Unlike vegetable crops, tree fruit and small fruit are not replanted every year and their roots are capable of absorbing nutrients any time the conditions are favorable. There is also a considerable amount of nutrient recycling. Nutrients in leaves that fall to the ground or brush that is cut from the trees and chopped in the orchard are recycled and made available again to the trees. Only a small portion of the nutrients are removed in the form of the fruit. Leaf analysis also can determine micronutrient levels in the tree. Soil tests for micronutrients are very difficult to validate.
The bi-annual Penn State Fruit Research and Extension Center Grower Field Day will be held Wednesday July 13th, 2011. The Field Day program will start at 1:00 pm and conclude with a barbecue dinner at 5:30 pm. Concurrent research and educational sessions will be held throughout the afternoon. A registration form is in the attached pdf.
Last week we observed the first brown marmorated stink bug egg masses and young nymphs in orchards, although the majority of the adults are still in surrounding areas of the orchards, feeding and reproducing on ornamental plants and woods. It appears that while the feeding on stone fruit was mostly concentrated on fruit, on apples the feeding happened mostly on foliage and growing shoots.
Natural enemies and environmental factors limit populations of insect and mite pests in natural ecosystems. When natural enemies are killed by man’s actions in any habitat or when pests are introduced to new habitats without their natural enemies, natural control often fails and results in pest outbreaks. Biological control of pest species by predators, parasitoids and pathogens has been a cornerstone of IPM since its inception. It has been difficult to utilize the full potential of biological control in tree fruit and other crops that receive periodic sprays of broadspectrum pesticides and/or have high quality standards. The best pest targets for biological control in tree fruit are generally the secondary foliage-feeding pests that do not cause direct fruit injury (i.e., mites, aphids, and leafminers). Populations of pests that feed directly on the fruit (i.e., codling moth, oriental fruit moth, and plum curculio) generally can not be tolerated at levels high enough for biological control agents to reproduce.
Updated disease infection models for apple scab, cedar apple rust, cherry leaf spot, and bacterial spot are attached.
In-depth educational training sessions to demonstrate airblast sprayer calibration will be held the week of June 20 at three locations in Pennsylvania. George Hamilton, University of New Hampshire Cooperative Extension, Agricultural Resources Extension Educator, assisted by Steve Gatcombe, will present an informative hands-on airblast calibration demonstration applicable to both small and large scale commercial farming operations. Five pesticide recertification core credits have been assigned for these meetings. For additional information, please email your questions to pesticide@psu.edu. The program is supported by grant funds, and there is no charge or need to register in advance.
The insect pest control observations and recommendations presented in this update are for the south-central part of Pennsylvania based on observations in Adams County. It is important to base your integrated pest management program on scouting observations in your own orchards.
Warm temperatures (70-85 degrees F) with light rains, heavy dew, and windy weather are most conducive for bacterial spot (Xanthomonas pruni) development and spread in stone fruit. Infections occur only when the leaves are wet, and the amount of disease increases exponentially. Bacterial spot infection periods in the graph were determined using a Spectrum Weather Monitoring System and Ohio State University Bacterial Spot of Stone Fruit model, HYG-3019-95. Graphs for apple scab, cedar apple rust, and cherry leaf spot infection periods are attached. Primary scab is still active but declining.
We re-ran the carbon balance model based on the weather data and forecast for Biglerville, Pennsylvania, and it shows several windows of carbohydrate stress in May 2011 when thinning may have been very strong. Based on the forecast as of Tuesday morning, May 31, 2011, the model predicts that there will be a block of time over the next three days when fruits will be very sensitive to chemical thinning because the temperatures are so high.
As much as we do not want to admit it, the brown marmorated stink bug, (BMSB), Halyomorpha halys (Stål) (Heteroptera-Pentatomidae) has established itself in our surroundings and most likely this insect pest will continue to pose an extremely serious threat to our agricultural systems for years to come. During the last two years researchers and extension specialists from throughout the Mid-Atlantic states have documented the enormous potential of this insect to destroy the quality of various fruits, vegetables and some agronomic crops such as soybean and corn. According to information recently gathered by Mark Seetin, the U.S. Apple Association Director of Regulatory and Industry Affairs, the estimated losses during the 2010 season for this region’s fruit growers exceeded $37 million.
Q. Is brown marmorated stink bug likely to be a problem on any of the berry crops, and if so, what materials are available to control it? (Tim Elkner, Penn State Cooperative Extension, Lancaster Co.) A. I was noticing a few brown marmorated stink bugs creep across the window as Tim was asking me this question, which wasn’t boding well. Last year, the berry crops most affected in the mid-Atlantic region were the ones that ripened later in the season after stink bug populations had increased, and I’d expect a similar seasonal effect this year as well. So, this would mean BMSB will likely inflict little or no damage on June-bearing strawberries, summer-bearing red and black raspberries, and early blueberry cultivars, and more damage on later-maturing varieties of blueberry and blackberries. Fall-harvested raspberries, blackberries, and day-neutral strawberries would be the most at risk.
Despite a relatively slow start for 2011, the degree accumulations base 43° at the Fruit Research and Extension Center (FREC) in Biglerville as well as the Penn State Research Center in Rock Spring (Centre County) are already the second highest for the last 6 years.
Expert advice, in the form of a farm energy audit, is the best method to find ways to improve your farm’s energy efficiency. Unfortunately, energy audits are often quite expensive and typically cost $1500 or more. Through the Pennsylvania Farm Energy Audits Program, USDA will offset the cost by paying 75% of the energy audit, leaving only 25% of the cost to the farmer. The audits are carried out by Penn State agricultural energy specialists or specially trained private consultants, depending on the location of the farm and availability of personnel. Dan Ciolkosz, the Penn State Extension energy specialist who is coordinating the program, let me tag along during one of the audit visits at a tree fruit orchard operation in Adams County last month. Dan was conducting the audit along with George Hurd, the Environmental/Resource Development Extension Educator from Franklin County. We first sat down with the orchard owner and asked questions about all of the different energy sources on the farm (e.g., electricity, fuel oil, wood, diesel, etc.) and looked over the farm’s electricity bills from the last few years. The owner also shared information about his use of and plans for improving and upgrading various buildings, cold storage rooms, and a three-phase electric system installation.
Faced with uncertainty about the future of brown marmorated stink bug populations and their impact on crop production, researchers at Penn State recently launched a stink bug mapping tool in collaboration with the PA Department of Agriculture. John Tooker, assistant professor of entomology in the College of Agricultural Sciences developed the tool with Douglas Miller, associate professor of geography and director of the Center for Environmental Informatics in the College of Earth and Mineral Sciences. The tool, housed at http://stinkbug-info.org, will help the researchers gather widespread data to study brown marmorated stink bug (BMSB) population dynamics. The BMSB is an invasive pest discovered in Pennsylvania in the late 1990’s. Although native stink bug species exist in the state, they have largely had a minimal impact on crop production. However, population explosions of the BMSB in southern Pennsylvania in 2010 caught many growers off guard, leading to questions about the biology and behavior of the pest. The researchers hope statewide tracking efforts will help them develop better management recommendations, as well as warn crop growers of impending damage.
At the Penn State Fruit Research and Extension Center in Biglerville, Pennsylvania, apple scab spore release is declining but still active. Apple scab, cedar apple rust, and cherry leaf spot infection periods and predictions through May 24th are attached.
Dr Alan Lakso at Cornell University has developed a carbohydrate balance model for apple, which we are testing for predicting fruit set. This model estimates carbohydrate supply and demand, and then calculates the carbon balance of the trees. During times of high supply and low demand (sunny and cool), the balance is positive and it is difficult to thin chemically. When the balance is slightly negative (0 to -20°F), chemical thinning becomes easier. When the balance drops to the range of -40°, the trees are under significant carbohydrate stress, and chemical thinning will be strong. Below -40°, the natural stress may be so severe that some fruits will be shed even when thinners aren’t used. Below -40° the response to chemical thinners is predicted to be very strong.
The insect pest control updates presented here are for the south-central part of Pennsylvania based on observations in Adams County, Pennsylvania. It is important to modify your integrated pest management practices based on scouting of your own orchard blocks.
Fruit growers report that this has been a challenging spring in terms of applying cover sprays, and now chemical thinners. Fortunately, a number of varieties were thinned last week when the temperature range was favorable. However, fruit size of some varieties was too small last week and these may still need to be thinned.
Some of you have contacted me wondering if we are still in the primary apple scab stage. There have been reports indicating that primary scab is over in neighboring states and it has also been suggested that ascospore maturation would progress much faster, and therefore terminate early in the kind of weather we are experiencing this spring. To clarify, today we counted ascospores in numbers that far exceed our monitoring threshold so we are still in the primary apple scab phase of the disease. Also, we observed the first fruits with apple scab symptoms on nontreated trees here at the Penn State Fruit Research and Extension Center this morning.
Dr. Greg Krawczyk and Dr. Larry Hull, entomologists at the Penn State Fruit Research and Extension Center in Biglerville, will be posting insect pest control updates, or "Insect Bytes" each Friday. The updates are based on observations in Adams County, Pennsylvania, and it is important to adjust the recommendations for your specific orchard conditions.
