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Understanding Crop Load Estimations and Weather during Spring Bloom

A Stressful Growing Time Made Easy with AgTech

Table of Contents

  • Overview of Spring Orchard Management for Growers

  • Crop Load Estimations and Labor

  • The Importance of Understanding Micro-Climates

  •'s role in Spring Fever


For most individuals the months of April and May mark the beautiful transformation from harsh, snowy winters to lush, flowery springs. People start enjoying time outside as the gentle buzzing of bees induces the sweet aroma of budding flowers. These factors are very true for orchard owners in the Pacific Northwest as they become just as busy as the bees pollinating their crop. As blooms start to develop and transform, growers utilize strategically placed pollinizer trees that give bees the opportunity to pollinate flowering blossoms as they search for nectar. Once the trees are pollinated these blossoms begin their transformation phase into growing fruit.

Contributing Factors of Pollination:

  • Pollinizer (source of pollen, pollinizer trees)

  • Pollinator (agent of pollen transfer, ex: bees, wind, moths, butterflies, birds)

  • Fruit Trees and bloom

  • Weather

As previously mentioned, growers place pollinizer trees around the orchard to give pollinators the opportunity to transfer pollen to other trees. Depending on the species of the tree, the plant can either be self-pollinated or cross-pollinated. The blossoms of a self-pollinated plant can be fertilized by pollen from the same tree or another tree of the same species, meaning the plant can provide its own source of pollen and doesn't need a strategically placed pollinizer tree. On the other hand, cross-pollinated plants can only set fruit when fertilized from another cultivar. This is where in apple orchards the placement of crabapples that give bees the pollen to cross-pollinate is crucial. Interestingly enough, despite the tree being a self or cross-pollinated plant, using bees and other pollinators allows the grower to produce more fruit!

Some varieties of apples are listed as self-fruitful (self-pollinators) but all varieties require some cross-pollination for fruit set. When cross-pollinated, apples will set fruit more heavily and more often.
Sour cherries are self-fruitful meaning they don't need a second cultivar for pollination; however, sweet cherries (except for Stella and Lapins) are self-unfruitful and do need a cross-pollinator. 

Now onto the business with bees. Bees act as the agent of pollination transfer to and from trees. There are approximately 1000 different species of bees in the world but only a few are actually affective in pollinating orchard crops in the Pacific Northwest (WSU: Honey Bees, OSU: PNW 692). As many of you may know, the wild bee population has recently declined which leaves the majority of work for orchard pollination to honey bees. This means that trees planted more than 100 feet away from bee hives may result in poor pollination. Bees are most effective in temperatures above 65 degrees. Bad weather and even strong winds may cause bees to stay in their hives and prevent them from doing their important work.

According to a WSU Honey Bees article, "About 50% of the honeybees foraging in Red Delicious apples are pollen collectors, but that number may increase in other varieties. Roughly 80% of the honeybee foragers in cherry orchards are collecting pollen."

Crop Load Estimations and Labor

This phase in the growing process means that growers need to hastily use a large labor force to count flowering buds to inform where and how much thinning needs to take place. In almost all cases, individuals walk the rows of an orchard to hand count buds and blossoms. Crop load management like this is crucial for a variety of reasons. Due to fruit trees generally producing more fruit than necessary, the trees need to be thinned to insure proper fruit size and quality.

Reducing the crop load in this year's bloom directly affects the crop load of the next year. Fruit trees make flowering buds for next season's crop during this growing season. Not enough thinning and proper sunlight is given to a majority of the fruit on the tree and nutrients are not shared proportionally, causing too many clusters of insufficiently sized apples. However, too much thinning will produce larger apples that are prone to storage problems and poor fruit quality.

Not only is springtime a crucial window for growers to properly manage fruit quality and quantity, but this crop load estimation derived from hand counting fruit blossoms directly impacts the price at which venders pay for growers' fruit this year and even the following year. Sometimes this number is underestimated, causing the grower to sell their product at a heavily discounted price. If growers were able to rapidly, accurately, and without a large labor force count fruit blossoms and buds, their time could be used to better manage other challenges on the farm. 


The Importance of Understanding Micro-Climates

Early frost damage affects blossom and overall fruit production of cherries and apples in Washington and Oregon. In some cases this can cause total crop loss. Being able to understand an orchard's micro-climate is a critical factor for growers to better manage their spring bloom. Micro-Climate weathers stations like those provided by WSU, Davis Instruments, Meter Group, and AgriNet allow growers to check current and forecasted temperatures across an entire farm or even specific blocks, giving them the opportunity to understand where those pressures are in real time. More often than not, growers are using weather stations from the nearest town which happens to be tens of miles, if not more, from their farm's location. The distance from the grower to the nearest station is not close enough for them to properly understand how their farm is going to be affected by the weather. Many growers even experience different climates and weather variabilities on their own farm, so a station miles away from their location does not give them valuable insights to make decisions.

It is increasingly common to see growers use irrigation and frost fans to control the amount of damage spring freezes cause to their crop. This seems absolutely absurd and contrary to standard logic: applying something that freezes to your high risk crop will actually help it. In order for the water to ice over and freeze it first releases the heat that originally keeps it a liquid. Typically damage doesn't occur to the crop until temperatures reach below 30 degrees Fahrenheit, so continuously applying new water that releases heat and then freezes keeps the sensitive blooms safe. (Image depicting this growing practice to the left) has previously discussed the importance of understanding an orchard's micro-climate in past post "Weather Sensor Partners."'s role in Spring Fever

After talking to countless growers and hearing first hand that this season involves a tremendous amount of time, stress, and money, proactively worked to form close relations and a strong partnership with Green Atlas. The Green Atlas Cartographer is an innovative combination of hardware and software that allows flower and fruit counts to be quickly and accurately mapped over entire orchards. With high resolution AI assisted mapping, our customers know every block and every tree, aiding management from flower to fruit. The use of this ATV-based imaging system makes processes like fruit thinning and crop load estimations virtually instant all while traveling at speeds up to 20+ mph. Instead of having to hire an entire workforce just for fruit blossom and bud counting, growers can simply utilize a single individual to drive one ATV to map out entire orchards. While on the freeze side of things, doing frequent scans to count for the difference in fruit will allow the grower to gain an indiction of what percentage of fruit has dropped.

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