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Caution for Apple Carbohydrate Thinning Model

Tree fruit physiologist and developer of the apple carbohydrate thinning model, Alan Lakso, Cornell University, advises caution when using the NEWA apple carbohydrate thinning model:

(1) The apple carbohydrate model assumes that the trees are healthy, with normal vigor, have no significant stress (frost, drought, nutrient) and no significant carry-over effects from previous years that might change the tree response to the weather.  With the severe drought in 2016, there may be orchards that will have a weakened state coming into 2017 which would likely make the tree abnormally sensitive to thinners.  So in those cases the model may suggest a stronger thinner concentration than is appropriate. Conversely, if irrigated last year, with the warm season and lots of sun, those trees may be in better than normal condition and harder to thin.

(2) With the cold spring weather period currently being seen across much of New York and the Northeast, flowering, pollination, initial set and early fruit growth may not be very well modeled because we did not have much data under these very cold (or also excessively hot) conditions when the model was developed.

For all these reasons, you should have less confidence in the model this year.  Use your experience with your unique situation.

Everyone, please pass this on to whomever might be appropriate.  Also please get back to Alan Lakso with your observations of when the model seemed to work or not work this season.  That will be critical to make appropriate adjustments or confirm knowledge of model limitations.

Here is Dr. Lakso’s email contact information:
Alan N. Lakso,  Professor Emeritus
Horticulture Section, School of Integrative Plant Sciences
Cornell University
NY State Agricultural Experiment Station
Geneva, NY 14456
Email (preferred)

The NEWA region spans from Minnesota to New Hampshire to North Carolina. For some regions this cautionary note may not apply, but it will be important to keep these aspects of the apple carbohydrate thinning model in mind for future years.

2016 Drought: Insights from New York Farmers

Thank you to all who participated in the drought survey last year. Here are the findings from the survey, written by Shannan Sweet and David Wolfe, School of Integrative Plant Science, Cornell University.

Key Findings

  • The record-breaking 2016 drought affected farmers across New York State (NYS) with more severe effects in Western and Central NY than Eastern NY.
  • Crop loss estimates from a late summer survey of over 200 farmers suggest that more than 70% of rainfed field crop and pasture acreage had losses greater than 30%, with some reporting over 90% crop failure.
  • Most fruit and vegetable growers who irrigate lacked the irrigation capacity and water supplies to keep up with the drought, and estimated crop losses of up to 35% were reported.
  • Common suggestions from farmers on help they could use in dealing with future drought included better long-range weather forecasts, financial assistance to expand irrigation capacity, and more information on drought resistant crops.


An unusually low winter snow pack, followed by lower than average rainfall and higher than average temperatures during the 2016 growing season (NRCC) led to continuously worsening drought conditions throughout New York State, and record-breaking low stream flows in Western and Central NY by late July and August (Drought Monitor). New York (NY) farmers have asked if they should expect more dry summers like the one we had in 2016 in the future with climate change. The answer to that is we don’t entirely know. Climate scientists are fairly certain that the number of frost-free days will continue to increase and summers will be getting warmer, which will increase crop water demand (Horton et al. 2011; Walsh et al. 2014).

Figure 1. Drought survey responses by county. Darker green colors indicate a greater number of farms (Source: 2012 USDA NASS, ESRI – 12-M249). Red dots designate counties that responded; larger dots indicate a greater number of respondents. The dotted line delineates Western (WNY) and Eastern (ENY) New York. Counties in WNY were those designated as “national disaster areas” due to the drought.

Climate models are less reliable for predicting rainfall and snow, but most projections suggest that total annual precipitation will remain relatively stable in New York, with small decreases in summer months and possible increases in winter.  Also, the recent trend of the rainfall we do get coming in heavy rainfall events (e.g. more than 2 inches in 48 hours) is likely to continue. This would suggest both flooding and drought will continue to challenge New York farmers, and it is possible that more severe short-term droughts in summer could increase in frequency. Given these projected impacts, we surveyed NY farmers throughout August and September, so as to better understand how farmers were affected by the 2016 drought and if they are able to cope with drought risk.  The survey was distributed online and in paper format with the help of Cornell Cooperative Extension and the Farm Bureau, and 227 farmers responded from nearly every county (Fig. 1). Though a majority of responses came from field crop farmers, vegetable and fruit crop farmers were also well represented (Table 1).

Drought Impact

Across the state, farmer-estimated crop losses for rainfed field crops, pasture, fruit crops and vegetable crops were 31%, 42%, 47%, and 46%, respectively (Table 1). Among fruit crops, rainfed grapes, known for relatively deep root systems, were markedly less affected by the drought than fruit trees (primarily apples) and berries (Table 1).

Figure 2. Percent of respondents that estimated crop yield losses within certain percent ranges for (a) rainfed and (b) irrigated crops. Data averaged across New York State.

Figure 2 illustrates that estimated crop losses of more than 30% were reported for rainfed field, pasture and vegetable crops, and some farmers reported losses above 90%. Significant crop losses were reported even for the irrigated acreage of fruit and vegetable crops (averaging 6% and 27%, respectively, Table 1). This reflects an inability to keep up with crop water demand on irrigated acres in 2016 in this severe and long-term drought. When asked what most limited their ability to maintain yields, 38% said limited water supply, 31% said inadequate irrigation equipment, and 18% said poor soil water holding capacity (data not shown). Other reported factors that most limited their ability to maintain yields, included: lack of time, labor costs, water costs, the need to rotate irrigation equipment through crops, excessively hot temperatures, damaged and malfunctioning equipment, and being unprepared in every way for needing to irrigate.

Additional comments from farmers related to the effect of the drought included statements about: extra costs associated with buying hay; having to sell cattle due to an inability to keep them watered and fed; and concern about the effect of the drought on next year’s crops (e.g. perennial fruit crops). Several farmers indicated factors that helped them get through the drought, including: cover cropping, no-till farming, increased soil health, and improved grazing management.

Figure 3. Western and Eastern NY (see Fig. 1) farmer’s rating of the economic impact of the drought.

The drought impact was so severe in Western NY (WNY) that the USDA-Farm Service Agency (FSA) declared most counties in this region “natural disaster areas” in 2016, and eligible for some financial relief in the form of low-cost loans (FSA). The more severely drought stricken farms in WNY reported higher crop loss for both rainfed and irrigated crops compared to Eastern NY (ENY) (Table 1). In WNY nearly 80% of farmers estimated the overall economic impact “moderate’’ to “severe”, and less than 20% considered it “minor” or just a “nuisance” with almost no economic impact.  Many farmers in ENY also felt a substantial economic blow, but only about half categorized the impacts as “moderate” to “severe”, and the other half referred to it as “minor” or a “nuisance” (Fig. 3).

Adaptive Capacity

The majority of fruit farmers who irrigated reported using drip irrigation (data not shown). Most vegetable crop farmers who irrigated used moveable sprinkler pipes and big gun sprinklers. In this extreme year, several farmers who lacked irrigation equipment reported using anything from hoses and hand watering to sprayers and garden sprinklers. Sixty-five percent of farmers reported using well and pond water for irrigation, 15% used city water, and 14% used streams, lakes, or canals. Other water sources used for irrigation included hydrants, cisterns and springs. Most farmers said ponds (45%), wells (24%), and streams (22%) proved to be inadequate sources of water this year. The 6% who claimed that city water was inadequate said it was the cost that was prohibitive.

When asked what criteria farmers used to prioritize which fields to irrigate 34% said crop value, 29% said crop sensitivity to stress, 21% said location to water source, and 8% said soil water holding capacity. Other factors used to prioritize where to irrigate included: which crops had a better chance of survival (e.g. mulched or weed fabric covered crops, crops in hoop houses or high tunnels), the maximum amount they could irrigate, the ease of irrigation (e.g. planting in plasticulture), the amount of water remaining in their irrigation source (i.e. how low was the pond), age of perennial crops, or soil moisture sensor readings. When asked what criteria farmers used to prioritize when to irrigate 38% said crop sensitivity to stress, 25% said weather forecast, 22% said crop value, and 11% said soil water holding capacity. Other criteria used to decide when to irrigate included soil moisture sensors and online tools (e.g. CSF water deficit calculator).

Farmers’ responses varied when asked what they might have done differently if they had known in advance how dry this summer would be (Fig. 4). A common response (22%) was

Figure 4. Production change farmers would have made if the drought could have been anticipated.

expand irrigation capacity, but many (36%) selected the “other” category and wrote in options that included suggestions related to increasing water availability (e.g. more ponds or wells), building soil organic matter and water holding capacity (e.g. cover crops and no-till), and many others.

Insights for Extension Educators, Researchers and Policy Makers

When asked how organizations such as Cornell Cooperative Extension, university researchers or government and non-government agencies could help them cope with future drought risk, farmers expressed interest in knowing more about:

  • Drought resistant crop varieties
  • Irrigation development and planning, irrigation options for perennial fruit crops, and gravity-fed irrigation
  • Improving soil quality and water retention, and water saving ideas
  • When and how to irrigate specific crops, and how soil moisture affects nutrient uptake
  • Pasture rotation, silvopasture, rotational grazing, and stockpiling forage
  • How to minimize the effect of drought (e.g. weed control and mulching)
  • What pests are more (or less) prevalent during a drought
  • Dealing with mental stress related to drought and climate issues

In response to that same question, farmers said they wanted more:

  • Development of online tools and better long-range forecasting
  • On-farm courses and training, and educational materials about agriculture and drought
  • Financial assistance to cover drought losses
  • Inventory of vacant farmlands for potential use
  • Financial assistance for irrigation equipment and ponds, and for soil improvement and water management
  • Rentable and leasable irrigation equipment, and cheaper county water for agricultural use
  • Cost sharing for: cover crops and no-till supplies, and for multi-purpose ponds

References and Hyperlinks

CSF (Climate Smart Farming) –

CSF water deficit calculator –

Drought Monitor –

Drought Survey –

FSA (Farm Service Agency) –

Horton R, Bader D, Tryhorn L et al. (2011). Ch. 1: Climate Risks. In: Responding to Climate Change in New York State: The ClimAID Integrated Assessment for Effective Climate Change Adaptation. New York Academy of Sciences. pp 217-254.

NEWA apple irrigation tool, Cornell Apple ET Model –

NRCC (Northeast Regional Climate Center) –

USDA (United States Department of Agriculture) –

Walsh J, Wuebbles D, Hayhoe et al. (2014): Ch. 2: Our Changing Climate. In: Climate Change Impacts in the United States: The Third National Climate Assessment. U.S. Global Change Research Program, 19-67.

This project was funded by Cornell University’s Atkinson Center for a Sustainable Future and The Nature Conservancy and done in collaboration with the Cornell Institute for Climate Smart Solutions (CICSS) For more information contact Shannan Sweet: 126 Plant Science Bldg., Ithaca, NY 14853; 607 255 8641,

Dan Olmstead starts as NEWA Coordinator Jan 1, 2017

We are very pleased to announce that Dan Olmstead has been hired for the full time NEWA Coordinator position …for the entire network!  Ring in the New Year!!  Dan will start in his Extension Associate position as NEWA Coordinator in the NY State Integrated Pest Management (IPM) Program on January 1, 2017.  Officially his first day will be January 3rd, since Cornell University will be closed for the Holidays until then.

Dan has a Bachelor of Science degree in Environmental Science from Nazareth College, Rochester, NY.  He has 15 years experience using open source (QGIS) and proprietary (ArcGIS) platforms and graduate-level training in design and use of geographic information systems. He received the first place award for GIS posters at a Rochester, NY conference and has created numerous GIS-based maps and figures for peer-reviewed publications.

His Master of Science degree is in Entomology from Cornell University, which he achieved in a short four years—while working full time as a Research Support Specialist on Insect Ecology and Vegetable Pest Management!  His MS thesis research was on corn earworm and titled New perspectives on the management of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in United States sweet corn: implications for 21st century production and IPM tactics.

The topic of his interview seminar was European corn borer, titled European corn borer and the evolution of insect pest forecasting, which is recorded on WebEx’ streaming recording link:  His seminar provides some really interesting insights on insect development, climate change, and day length. Plus, he provides an overview of his experience and vision for the position.

Dan stated in his application, “I am very excited about this position when I consider my experience, your needs and the future potential it holds not only for myself, but for the New York State IPM Program and all the stakeholders that utilize NEWA and its management tools” (emphasis added). That means You!

Please join me in welcoming Dan Olmstead to the position of NEWA Coordinator!

Juliet Carroll, Leader of NEWA and Fruit IPM Coordinator, NYS IPM Program