Nematode Threshold & Treat, Monitor or Safe
Protects vegetables
Enter nematodes per 100 cc and the crop's damage threshold to get the ratio and a clear action — treat at or above the threshold, monitor as you approach it, or stay safe well below.
Compare your soil count
Next: population is at or above threshold — plan a nematode management programme (resistant variety, rotation, soil amendment or nematicide) before planting.
Thresholds vary by crop, nematode species, soil type and assay method. Confirm with your local diagnostic lab's recommendation.
Nematode threshold — key facts
- Ratio
- count ÷ damage threshold
- Treat
- ratio ≥ 1 (at or over threshold)
- Monitor
- ratio 0.5 to 1 (building)
- Safe
- ratio < 0.5 (well below)
- Count basis
- nematodes per 100 cc soil
- Threshold
- varies by species and crop
- Measure with
- lab soil extraction
- Privacy
- Runs in your browser; nothing uploaded
A count means nothing until you compare it to the threshold
A nematode count on its own does not tell you whether to act — the same number can be harmless for one crop and damaging for another. What matters is the count measured against the crop's damage threshold. When the population reaches that threshold, yield loss begins and control pays off; below it, treating wastes money. This tool turns the raw count into a ratio and a plain decision.
It gives the threshold ratio, the action, your count and the threshold from the soil count and the damage threshold you enter. Use it to read a lab report at a glance, decide between rotation, resistant varieties or a nematicide, and time resampling. Pair it with the Leaf Wetness Disease Risk, Pesticide Residue Decay and Weed Density Survey tools for a full crop-protection plan.
Read the lab report fast
Turn a count into treat, monitor or safe instantly.
Treat only when it pays
Act at the threshold, not before it.
Catch a building population
The monitor band flags counts on the rise.
Match crop to threshold
Use the threshold for the crop you'll grow.
Frequently Asked Questions
How is the action decided?+
By the ratio of the soil count to the crop's damage threshold. Ratio = nematodes per 100 cc ÷ damage threshold. At a ratio of 1 or more the count has reached or passed the threshold, so the tool says treat. From 0.5 up to 1 it says monitor — the population is building toward damage. Below 0.5 it reports safe, well under the level where yield loss begins.
What does nematodes per 100 cc mean?+
It is a count of plant-parasitic nematodes extracted from a standard 100 cubic centimetre (about 100 gram) portion of soil. Labs report counts on this basis so results can be compared against published damage thresholds. Enter the lab figure for your sample, or your own extraction count standardised to 100 cc.
What is a damage threshold?+
It is the nematode population at which a crop starts to lose measurable yield — the point where treating pays off. Thresholds vary by nematode species, crop and soil type; root-knot on a sensitive vegetable has a much lower threshold than a tolerant cereal. Use the published threshold for your specific nematode-crop pairing.
Why a treat line at a ratio of 1?+
A ratio of exactly 1 means the count equals the damage threshold — the population has reached the level where economic yield loss is expected. At or above that line the cost of control is justified by the yield it protects, so the tool recommends treatment. Below it, the loss does not yet warrant the spend.
Why a monitor band from 0.5 to 1?+
Nematode populations build over a season. A ratio between half the threshold and the threshold means damage is approaching but not yet certain — the right move is to monitor, resample later, and be ready to act if the count climbs. Treating this early can waste money on a population that may not reach the damaging level.
How should I sample the soil?+
Take many small cores across the field, mix them into one composite sample, and keep it cool and out of the sun before sending to a lab. Sample at the right depth in the root zone and at a consistent time of year so counts can be compared to thresholds and across seasons. Poor sampling is the biggest source of misleading nematode results.
Does the crop change the threshold I should enter?+
Yes. The same nematode count can be safe for a tolerant crop and damaging for a sensitive one, so the threshold you enter must match the crop you are about to grow, not the one just harvested. Always pull the threshold from guidance for the planned crop and the nematode species present.
What are my options if it says treat?+
Options include rotating to a non-host or resistant crop, using nematode-resistant varieties, soil amendments and biofumigation, fallow or solarisation, and registered nematicides where allowed. Cultural and rotational tactics are often cheaper and more durable than chemicals; the ratio simply tells you that doing nothing risks yield.
Are the figures precise?+
They're solid working figures for a decision. Nematode counts are variable and thresholds are guidance, not hard cut-offs, so treat the ratio as a strong signal rather than a guarantee. Confirm with lab results, local advice and field history before committing to a costly treatment.