By Matt Smith
Editor’s note: This article grants one continuing education unit (CEU) in the Core category toward the renewal of a Florida Department of Agriculture and Consumer Services restricted-use pesticide license when the accompanying test is submitted and approved. This article is an updated version of a previous article, “Scouting: The Tip of the IPM Spear,” published in the February 2020 issue of Citrus Industry magazine. .
Did you ever see “Top Gun: Maverick”? On the surface, it’s a perfect blend of a sports movie and “Star Wars: A New Hope,” but it’s actually about the importance of having a proper scouting program. In the film, a hostile country’s unsanctioned uranium enrichment plant is discovered in an underground bunker in a valley. In response, a group of the U.S. Navy’s best fighter pilots are tasked with destroying the plant before it becomes operational. Sounds like a job for the stealthy F-35 jet, right?
Wrong. Thanks to thorough scouting by U.S. intelligence, we learn that the enrichment plant is defended by state-of-the-art GPS-jamming technology and an extensive surface-to-air missile array, necessitating a low-level, laser-guided strike tailor-made for the F-18. Furthermore, satellite images of a nearby base reveal a squadron of 5th-generation fighters (that definitely aren’t Su-57s) and even some F-14s. The scouting doesn’t stop there. Later in the film, a follow-up scout reveals that the mission will need to be moved up a week, necessitating a few changes in the approach.
The same need for accurate and timely threat data exists on the farm. While it would be nice to be able to trust that Plot A or Row B3 is doing just fine out there, the reality is that problems in the field start small and, depending on the source of the problem, can spread rapidly. Early detection and accurate pest identification are key to preventing a small, easily treatable problem from growing into a massive, expensive undertaking. Early detection only happens when you’re looking in an area that wasn’t showing any obvious problems. A scheduled scouting program is a must-have tool on your farm.
Scouting requires both the frame of mind to be attentive to changes in the landscape and the right equipment to inspect problems, collect samples and record helpful information. Some examples are:
- Hand lens with 10–20X magnification — to examine leaf spots, insects, etc. Some jeweler’s loupes have integrated flashlights that make it much easier to see pests hiding in shadows.
- Digital camera — Cell phone cameras have come a long way, and even older phones can take great pictures. Submitting photos along with a sample to the diagnostic lab can greatly assist your technician. Take closeup photos of the problem as well as photos of the whole plant and the surrounding area.
- Clipboard, pen, pencils, smart phone or tablet — for recording data. A technique I’ve seen work very well is to create a Google form or something similar where a scout can note the date, block and symptoms or pest found. Standardizing data collection methods can improve recordkeeping, identify recurring problems and predict when they may arise again. Think of it as a data link for your farm.
- White paper — Pests can be difficult to spot on the plant. Placing white paper under a branch or flowers and giving a good shake or tap can dislodge those pests. When they land on the paper, they’re much easier to see.
- Sweep net — for collecting flying insects from foliage. In “Top Gun: Maverick,” a much larger version of this was able to catch an F-14 on a carrier deck.
- Hand trowel — Leaves and flowers aren’t the only places that can show symptoms of a problem. A careful examination of the roots is always a good idea, especially when plants show signs of dieback or stunting. Save your fingernails and have a trowel handy.
- Soil probe — useful for taking soil core samples, mainly for seasonal soil testing or when nematodes are suspected. The presence of nematodes at damaging levels can only be confirmed by a trained eye using a microscope.
- Shovel —Think of it as an oversized hand trowel. Sometimes looking at the roots means digging deep. Sometimes your best bet is to send in a whole plant for analysis. For both those scenarios, use a shovel. A shovel can also be used in lieu of a soil probe for soil samples.
- Soil pH test kit — Do you suspect nutrient deficiencies are the source of your problem? A lack of fertilizer may not be the problem. At a certain pH, many nutrients become unavailable to your plants. Simple pH test kits are inexpensive and, while not as accurate as a lab test, provide a solid foundation for determining the source of a problem.
- Pocket knife, pruning shears and saw — Use these for taking samples.
- Rubbing alcohol, bleach solution or other sanitizing solution — for sanitizing your knife or pruning shears between cuts, especially if sampling from multiple plants. Sanitizing your tools reduces the chance of spreading the problem around the farm. Soap and water are good for cleaning tools of dirt and debris, but they are not effective at sanitizing them.
- Plastic bags/markers — for storing vegetative samples and labeling them. If submitting samples to a diagnostic lab, make sure the labels match the sample ID on the lab form.
- Sample vials — for storing insect samples. If mailing, consider filling the vial with rubbing alcohol (70%) to prevent damage to the sample from jostling around during transport.
Scouting takes time. So, the first thing you’re going to want to do is schedule scouting over a period of time based on the size of your farm. Don’t try running through the field at Mach 10 with a hand lens; patience pays off.
A small farm might only scout weekly, adjusting to the season’s pest pressure as required. Conversely, a large farm could divide the task, thoroughly checking portions of the farm daily to cover the entire field each week. Inspecting every single plant on large farms might prove impractical, but dividing the farm into sections allows thorough inspection of sampled plants from each.
For tree crops like citrus that require changing elevation to get a full picture of the plant, you can increase efficiency by checking the canopy and understory on alternating rows and repeating the process the next day so that by the end of the week the entire tree has been inspected. Scheduling scouting integrates it into the weekly routine, prioritizing its role in the farming process and preventing it from being overlooked in favor of other tasks that always pop up throughout the season.
Things that are out of the ordinary during scouting — like leaf spots, stunting, leaf deformations and unusual colors — are on your radar, but you’re also looking for patterns. Patterns serve as indicators and can help determine whether a problem stems from a pest or if the problem is the result of human error like herbicide damage. One of the biggest clues that a problem is human in origin is the presence of straight lines, a feature not commonly found in nature. Biological threats occur more in a sort of blob shape that starts small and slowly expands out as the pathogen or insect spreads out as opportunity allows.
It can also be helpful to look for natural predators as an indicator. Predators tend to be larger than their prey. In “Top Gun: Maverick,” after Mav’s aircraft crashes, his wingman Rooster finds him not by actually seeing Maverick from the air but by identifying the much larger attack helicopter firing at him. In the same vein, ladybugs are much easier to spot than aphids.
SECURE PROPER ID
Proper pest identification holds major significance for both environmental and economic sustainability. Not all problems in a grove share identical solutions. For example, applying a fungicide because you notice leaf spots may not suppress the problem if the cause is actually bacterial. Applying an insecticide because you see holes in the leaves is a waste of money if you applied a pesticide that is effective at the wrong growth stage.
In an integrated pest management program, proper pest identification is of primary importance. Upon noticing something out of the ordinary in the field, first closely inspect the plant. Use your magnifying glass to look for insects or spores around leaf spots. Use your digital camera to take pictures of any damage. If the plant is stunted or is showing signs of nutrient deficiency despite proper fertilization, inspect the roots using your hand trowel or shovel. Use your pocketknife or shears to take samples and collect them in labeled bags.
Take notes on the date, the extent of the problem, the variety of plant, the location and the weather. Go back to your pesticide application records to see what pesticides have been applied within the past 45 days. You may not be able to identify the source of an issue in the field yourself, but the samples and information you collect can be critical for specialists in a plant pathology lab to provide a positive identification later.
By keeping good records and understanding what issues affect your farm, you can predict when problems will arise in the future and take proactive steps to reduce damage in years to come. If you found a certain insect causing damage, you can use the knowledge gained from studying that insect’s life cycle to predict when it will show up again and know to scout for it.
Flying insects present a particularly challenging issue. Their enhanced mobility make them difficult to spot on an affected plant. Setting up traps will make scouting for these pests easier. For example, if you find damage from chilli thrips one year, you can set traps or make a point to scout for them the following year and spray pesticides when you know they’re in the field instead of spraying blindly for months on end.
While drones may be the future, purposeful human scouting remains a foundational component of a properly designed integrated pest management strategy. Scouting allows a grower to catch problems early, potentially saving money and reducing the amount of pesticides that need to be deployed in the environment.
- Applying Pesticides Correctly by Frederick M. Fishel
- Scouting for Citrus Greening by Jamie D. Yates, Stephen H. Futch and Timothy M. Spann
- Integrated Pest Management Scouting in Field Crops (E3294) by James DeDecker
- How to Scout by C. White, Pesticide CEU Day class module
Matt Smith is a commercial crops and food systems Extension agent with the University of Florida Institute of Food and Agricultural Sciences in Tavares.
To request a hard copy of the article and test, or if you have questions regarding this article, test or CEUs, email Matt Smith at email@example.com or call 352-343-4101 ext. 2729. Please allow two weeks to process your CEU request.