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Man with notebook in a field.

Keys to Investigating and Diagnosing Crop Protection Disrupters

Originally published December 19, 2022

croplife magazine


Depending on where you’re reading this, it’s the end of the season. For most crops, harvest has wrapped. Equipment is being winterized. Crop plans for next year are being sketched out.

This is also a time of reflection, and a common topic of conversation between retailers and their growers is the “What went wrong?” discussion. We typically address the issue as soon as it pops up, but, in some cases, it helps to reflect on the past to help us explore new methods we might consider adopting to prevent the same mishaps and better plan for the future.

A big component to help our detective work move quickly in the field or orchard are our processes. Let’s focus on how we can investigate potential crop challenges in the moment quick and more effectively.

Where Do We Start?

When we begin exploring causation, we need to recognize there could be countless variables influencing crop protection related issues, from soil conditions and irrigation to large animals and application methods. Prior to heading into the field or orchard, it’s key to arm oneself with contextual knowledge. When playing the role of detective, there are four key steps to follow to get the ball rolling:

  1. Start with the grower or consultant who flagged the issue. They likely know the ins and outs of the operation and can help you name some of those influencing factors: which areas are hard to keep irrigated, where there is more organic matter, the soil composition, what crops were planted in previous seasons.
  2. Request visuals. Imagery, whether it be drone or eye level, paints the picture for us of what transpired in-season and plays an important role as reference material. Dates of when photos are taken are important as well.
  3. Find historical records of spray applications. If the concern is a spray malfunction, a record of application date, active ingredients and rates used will contribute to our investigation into determining a cause.
  4. Look into local resources. Think of your local university extension members, colleagues and partners. The former helps with background on areas like resistance screening of weeds, diseases or insects that are suspected as the culprit. Colleagues or partners in the area may have institutional knowledge you can tap into or experience with similar issues to compare evidence to.

Telltale Signs Something Is Not Right

When I walk into an orchard, the first thing I am looking for is inconsistencies in foliage color and overall plant health: wilted or discolored leaves, physical damage or cankers on the bark. On the flip side, a field can be more obvious with its signs. Any issue tends to stand out more in this environment and causation can be easier to pinpoint.

Regardless of if it’s a field or orchard, there are a few common indicators we look for during and outside the growing season.

Application Inconsistency

Unusual and visible patterns are a quick way to determine if the issue was caused by a failed spray. In the case of a herbicide drift issue, there will often be border effects. This also helps address where the problem occurred, and we can reference back to that moment to root out a cause. Drift in the case of temperature inversions appear differently. It’s not as obvious as wind drift — which has directional hints as to what happened because the application was made ‘over there’ — but the damage looks like you sprayed ‘over here.’

Product Failure

Did the product simply not work at all? Something like insecticide failure is apparent as insects are still mobile. This leads us down the thread of what rate was used, how quickly was the applicator moving through the crop and timing of the spray. The life stages of insects also should be considered, as they could have developed more between the time of scouting and spraying. Also, knowing what to expect is highly important. Something might look like a failure at Day 1 after treatment, but the active ingredient may only need a little more time and by Day 3 after application we’re satisfied with the level of control.

Piecing the Findings Together

Figuring out what went wrong on an operation is time consuming and, unfortunately, there are typically a cascade of factors contributing to the problem at-hand versus a single culprit. Now, at this point, there isn’t much you can do, but you can set yourself and your growers up for greater success in the future by acting prophylactically.

My parting advice: There are three rules you and your grower can follow, regardless of the input, to help reduce the likelihood of problems or extensive detective work in future seasons.

  1. Don’t cut corners when it comes to scouting.
  2. Keep meticulous records to help speed up the detective work.
  3. Follow the label and don’t skimp on the rate. Like anything in farming, the more you put in, the more you get out.