By Blake Jackson
As spring arrives agricultural landscapes, soybean farmers should prioritize soil sampling for soybean cyst nematode (SCN), a significant threat to yields.
The Penn State Extension-Agronomy Team, with support from the Pennsylvania Soybean Board, offers free nematode testing for Pennsylvania soybean growers, underscoring the importance of proactive management.
SCN ranks as the most destructive soybean pathogen in the US and Canada, capable of causing yield reductions of up to 50%. Its insidious nature lies in its ability to persist unnoticed for extended periods, making routine soil testing crucial even in seemingly healthy fields.
The nematode's resilience allows it to survive in the soil for years, even without a soybean host, and its long-distance spread occurs primarily through the movement of contaminated soil and root fragments.
Detecting SCN presence relies on two key methods: field scouting and soil testing. Scouting involves carefully excavating soybean roots approximately six weeks post-planting to visually inspect for SCN females.
These appear as tiny (1/32 inch), white, lemon-shaped structures attached to the roots and are visible to the naked eye.
Soil testing offers a more quantitative assessment of SCN populations. While samples can be collected at any point during the growing season if SCN is suspected, the current period is opportune.
The recommended sampling technique involves collecting at least 20 soil cores, 6-8 inches deep, in a zig-zag pattern across areas of 20 acres or less.
Special attention should be paid to high-risk zones such as field entrances, flood-prone areas, low-yielding spots near storage buildings, and high pH regions.
For each field, the collected cores should be thoroughly mixed in a bucket, and at least two pints of this composite soil placed in a sealable bag.
To maintain sample integrity, it's vital to protect them from heat and direct sunlight and refrigerate them (avoiding freezing) until laboratory submission.
This proactive approach through soil testing empowers growers to understand their SCN risk and implement timely management strategies.
Before mailing, clearly label each sample bag with your name, phone number, email, address, field address or GPS coordinates, current crop, previous crop, and the field's acreage. Additionally, write “for SCN testing” on or inside the shipping box.
To take advantage of this free testing service, send your samples to:
Penn State
Dr. Dilooshi Weerasooriya
361 Science Dr., Room 211
University Park, PA 16802
Categories: Pennsylvania, Crops, Soybeans