Moving Pathogens in Infested Soil on Equipment

Apr 17, 2020

By Ana Maria Pastrana and Tom Gordon

Hey folks this concept of transmitting fungal inoculum from field to field on people's feet and equipment has been one I've been talking about for a while, and now here you have the scientific evidence from some of our finest scientists at the UC. Really appreciate the two of them sharing these important results with us.

Soilborne diseases are caused by pathogens that reside in soil, such as Fusarium oxysporum, Macrophomina phaseolina, and Verticillium dahliae. They can survive for long periods of time as resistant structures. For this reason, soil carried on equipment can be a source of inoculum. To demonstrate this, we did an experiment in which a tractor was driven through a field where a pathogen was present. We sampled soil attached to the equipment to test for the pathogen. We also had a person walk through the field, and sampled soil attached to his boots.

The trial was run in February 2020 at the Plant Pathology Research Farm on the UC Davis campus. The field we used had an established population of Fusarium oxysporum f. sp. lactucae, the cause of Fusarium wilt of lettuce. We quantified inoculum as colony forming units per gram of soil. Colony forming units (CFUs) are either survival structures or crop residue colonized by the pathogen. Using this measure, the infested field had 243 ± 154 CFUs per gram of soil. This represents the average ± the standard error (a measure of variation across replicates). Soil collected from tractor wheels and the tiller confirmed the presence of the pathogen at 60 ± 19 CFUs per gram. The pathogen was present at 56 ± 18 CFUs/ per gram of soil removed from boots.

Infested soil on equipment or boots could introduce the pathogen to a new location. For this reason, it is advisable to wash soil off of farm equipment and shoes before moving between fields. This should be done routinely and not just when a field is known to have a pathogen. A pathogen may be present in a field, but not at levels high enough to cause disease. Consequently, no field should be assumed to be free of pathogens.

Tractor in the experimental plot infested with Fusarium oxysporum f. sp. lactucae.

Soil brushed from tiller and tractor tires onto a plastic tarp.

Collecting soil from boots.

Source : ucanr.edu

Video: Seeing the Whole Season: How Continuous Crop Modeling Is Changing Breeding

Plant breeding has long been shaped by snapshots. A walk through a plot. A single set of notes. A yield check at the end of the season. But crops do not grow in moments. They change every day.

In this conversation, Gary Nijak of AerialPLOT explains how continuous crop modeling is changing the way breeders see, measure, and select plants by capturing growth, stress, and recovery across the entire season, not just at isolated points in time.

Nijak breaks down why point-in-time observations can miss critical performance signals, how repeated, season-long data collection removes the human bottleneck in breeding, and what becomes possible when every plot is treated as a living data set. He also explores how continuous modeling allows breeding programs to move beyond vague descriptors and toward measurable, repeatable insights that connect directly to on-farm outcomes.

This conversation explores:

• What continuous crop modeling is and how it works

• Why traditional field observations fall short over a full growing season

• How scale and repeated measurement change breeding decisions

• What “digital twins” of plots mean for selection and performance

• Why data, not hardware, is driving the next shift in breeding innovation As data-driven breeding moves from research into real-world programs, this discussion offers a clear look at how seeing the whole season is reshaping value for breeders, seed companies, and farmers, and why this may be only the beginning.