Spray Technology In The Nut Orchard

Spray Technology In The Nut Orchard

Spray Technology

Efficacy, Efficiency, Environment. These are the three equally important concerns during any agricultural spray application. Nowhere are these concerns more challenging than in tree nut crops. Less pruning, new pesticide chemistries, high market standards for nut quality, and environmental concerns are squeezing the status quo for orchard spraying in nut crops.

What will the orchard sprayer look like in 10 years? My crystal ball is a little fuzzy, but here is a review of some current nut orchard challenges and general vineyard/orchard sprayer trends that could help shape the nut crop sprayer of 2020.


Pruning mature nut trees is now much less common than just a decade ago. One result is more shade in the lower portion of the canopy and more of the crop found higher in the tree. This means conventional air blast sprayers must push air through a large space to effectively protect the entire crop.
Newer, more selective pesticides reduce off-site drift and runoff risks, but up the bar for spray coverage. Many of these new pesticides must be eaten by the pest to kill it. Excellent coverage is therefore needed to deliver effective pest control.

Nut Quality

There is an increased focus on nut quality in the marketplace. An example is aflatoxin in almonds and pistachios. The European Union has very tough standards for aflatoxin and loads of nuts can be rejected if those standards are not met. Navel orange-worm damage increases the chance of aflatoxin contamination of the nut. Good pest control is a key to strong marketing of growing nut volume.

Off-site movement of pesticides is getting more regulatory attention. Air quality, water quality, and health of endangered species such as salmon and steelhead are concerns. Until drift and pesticide runoff are addressed, growers will face a risk of regulatory-based reductions in pesticide use options.

New Technologies

Where do these recent developments leave spray technology in nut crops? Here are some of the newer technologies being used in tree and vine crops in general.

Tower and wrap-around sprayers are becoming more common in grapes and small tree crop growing. These machines deliver the spray from the side or around the tree or vine. The spray is efficiently delivered and spray drift significantly reduced. Unfortunately, many nut crop trees are too tall for wrap-around sprayers and the 12- to-15-foot tall tower machines currently designed and used in grapes, apples, and other trees where the fruit is hand-picked.

But, could tower sprayers be developed for nut tree orchards? Towers help reduce drift and maximize the delivery of spray to the target. Mechanical hedgers and toppers are increasingly used in nut orchards. These machines could be used to cut slots or gaps down a tree row to allow tower sprayers access to tall, dense nut tree canopies. Autosteer systems could keep sprayers tracking down the middle of those slots.

Sensor-triggered sprayers can help reduce drift and pesticide runoff without reducing spray coverage. These units use one or more laser or ultra-sonic sensors per sprayer side to turn on the sprayer when a target is there and off when there is no tree to spray. These units can lower pesticide use per acre compared with “blind” spraying. The layout and age of the orchard can affect the amount of savings. Increased maintenance costs and complaints of temperamental electronics plague some models and hold down adoption of this promising technology.

Electronic Flow Controllers

Electronic flow controller use on canopy sprayers is another growing trend. This equipment matches sprayer output to ground speed and ensures accurate delivery of the intended spray volume and pesticide. Blueline and Turbo-Mist Sprayers, and perhaps other manufacturers’ equipment, can be fitted with rate controllers. Currently, most electronic flow controllers adjust sprayer pressure to change flow rate, which can, depending on the sprayer design, affect droplet size. Pulse width modulation technology changes sprayer output without changing system pressure. It is not available on orchard sprayers, yet. The nut orchard sprayer of the future will address all of these concerns equally. Funding from the almond and pistachio industries is currently supporting research on spray application and effective pest control in those crops.