Pest Spray Thresholds

What is the threshold for spraying against gout fly in cereals?

Spray if more than 50% of plants at GS12 have eggs present.

What is the threshold for spraying against grain aphid before GS61?

They should spray if 50% or more of tillers show grain aphid infestation.

What is the grain aphid spray threshold from GS61 until two weeks before grain fill in cereals?

Spray if 66% or more of tillers are infested with grain aphids.

How can barley yellow dwarf virus (BYDV) spray timings be determined in cereals?

Apply treatment when 170 day-degrees have accumulated since emergence or since the last aphicide application.

What is the threshold for spraying against OWBM in milling wheat?

Spray if there is 1 midge per 6 ears in milling wheat fields.

What is the threshold for spraying against OWBM in feed wheat?

Spray if there is 1 midge per 3 ears in feed wheat crops.

Under what conditions should wireworm be control by seed treatment in cereals?

If there are more than 750,000 wireworm larvae per hectare, treat seed with Signal 300 ES.

What is the slug treatment spray threshold in cereals?

If 4 or more slugs are found per refuge trap, pellet application is recommended.

What are the pollen beetle spray thresholds for oilseed rape (OSR) at different plant densities?

• Fewer than 30 plants/m² - 25 beetles per plant

• 30–50 plants/m² - 18 beetles per plant

• 50–70 plants/m² - 11 beetles per plant

• Over 70 plants/m² - 7 beetles per plant

How many pollen beetle must be present to warrant spraying in OSR if plant density is less than 30 plants/m²?

25 beetles per plant

How many pollen beetle must be present to warrant spraying in OSR if plant density is 30–50 plants/m²

18 beetles per plant

How many pollen beetle must be present to warrant spraying in OSR if plant density is 50–70 plants/m²

11 beetles per plant

How many pollen beetle must be present to warrant spraying in OSR if plant density is over 70 plants/m²

7 beetles per plant

How does the cabbage seed weevil spray threshold differ in northern and southern UK OSR?

• North: Spray if more than one weevil per two plants

• South: Spray if more than one weevil per plant

What is the threshold for spraying against mealy cabbage aphid in winter OSR?

Apply insecticide if 13% of plants are infested.

What is the threshold for spraying against mealy cabbage aphid in spring OSR?

Spray if 4% or more of plants are infected.

What is the threshold for spraying against pea aphid in combining peas?

Treat if 20% or more of the plants have pea aphids.

What is the threshold for spraying against pea aphid in vining peas?

Spray if 15% of plants are infested.

What is the threshold for spraying against thrips in pea crops?

Spray if 4 to 5 thrips per plant are found and the crop cannot outgrow the damage.

What is the threshold for spraying against pea moth in combining peas?

If 10 moths are found across both pheremone traps on two consecutive visits

What should you do once the threshold is hit for pea moth in combining peas?

• Start recording the max and min daily temperatures.

• Using the egg development calculator that comes with the pheromone traps, calculate the % egg development for each day, adding up the values until 90% development is reached. That is when you should spray.

• Spray again two weeks later

What is the threshold for spraying against pea moth in vining peas?

Just 1 moth caught requires a treatment in vining peas - apply a single insecticide application at flat pod stage

What is the threshold for spraying against silver y moth in peas?

Spray if at least 50 moths are caught by the first pod set.

What is the threshold for spraying against black bean aphid in beans?

Treat if between 5% and 10% of plants show dense aphid colonies.

When should bruchid beetle be controlled in beans during pod formation?

• Spray once after two consecutive days above 20°C

• Repeat seven days later if necessary

What is the spray threshold for slug control in potatoes?

Apply pellets when there is 1 slug per trap, using ferric phosphate if desired.

What is the threshold for spraying against peach potato aphid in sugar beet?

• Up to 12 leaves: Spray if 1 aphid per 4 plants

• 12 to 16 leaves: Spray if 1 aphid per plant

What is the threshold for spraying against peach potato aphid in sugar beet up to 12 true leaves?

Spray if 1 aphid per 4 plants

What is the threshold for spraying against peach potato aphid in sugar beet between 12 and 16 true leaves?

Spray if 1 aphid per plant

What is the threshold for spraying against beet leaf miner in sugar beet?

Spray if the number of eggs plus living larvae per plant exceeds the square of the current true leaf count per plant.

What is the threshold for spraying against silver y moth in sugar beet?

If 5 or more caterpillars per plant are found