USDA LTAR Common Experiment measurement: Crop scouting for pests and diseases
Brook J. Wilke
Long-Term Agroecosystem Research
LTAR
USDA LTAR
Common Experiment
crops
pests
cropland
growing season
crop scout
abiotic stress
nutrient deficiencies
Disclaimer
This research is a contribution from the Long-Term Agroecosystem Research (LTAR) network. LTAR is supported by the United States Department of Agriculture. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the United States Department of Agriculture or the Agricultural Research Service of any product or service to the exclusion of others that may be suitable. USDA is an equal opportunity provider and employer.
Abstract
Measuring pest and disease frequency and abundance can be cumbersome but contributes to important knowledge for research and management of cropland sites. Most LTAR Sites are assumed to lack the combination of knowledge and time to appropriately monitor crops for pests and diseases across the growing season. This protocol provides a format for hiring a contracted crop scout to monitor pests and diseases throughout the growing season.
Steps
Sample collection, processing, and analysis
Hire a professional crop scout to observationally scout all treatments every other week throughout the growing season.
- During each visit, include one replication at the plot and field scale for all treatments and rotation entry points. Rotate to a different replication at each subsequent visit so that all replications are visited equally over the year.
- Project managers should have continuous monitoring of pests and diseases to inform these visits, and at least one manager should accommodate the crop scout during each visit.
Crop scouts should be monitoring crops for:
- fungal diseases
- viral diseases
- insect pests
- vertebrate pests
- weed invasions
The scout may advise sending samples to a laboratory for diagnosis, as some diseases and pests may be unidentifiable in the field.
LTAR Sites may choose to monitor specific pests or diseases more intensively. This activity could include a pest or disease that is particularly impactful to the crops grown at the site or occurs in narrow windows of time not accurately captured by the bi-weekly crop scout visits.
- Site staff should develop a sampling plan including observations by the crop scout but layers more intensive observations and sampling by site staff.
Covariate metrics to be sampled concurrently
Scouts should also make other crop observations while examining the plots and fields, including:
- GPS coordinates for observation locations
- crop phenological stage
- abiotic stress (e.g., drought and soil crusting)
- plant population
- nutrient deficiencies
- other crop observations
Calculations
The calculations vary depending on the disease or pest the crop scout identifies. When feasible to quantify disease or pest levels, the site may want to calculate this level based on a unit of area or other units commonly used to make management decisions.
- For example, some management thresholds may involve the number of insect pests per plant, whereas others may be calculated per acre or hectare. The most important aspect is documenting the pest level for scaling according to future needs.
Quality assessment and quality control
Follow similar protocols within and across seasons. If different scouts are hired over time, ensure consistency in monitoring protocols is sustained.
Archiving
Record and save a paper or digital log of each visit. Some diseases or pests may be archived for future investigation or curation. The specifics of these archives are up to each site.
