IPM - Winter OSR

If the Bayer Pollen Beetle Predictor alerts you to the possibility of migration, it is time to visit fields to assess pollen beetle populations (average number of beetles per plant). Compare this with the revised HGCA recommended control thresholds to decide whether or not treatment is required.

When Bayer Pollen Beetle Predictor shows conditions suitable for migration it’s time to visit fields to monitor pollen beetle populations (average number of beetles per plant). Compare findings with the revised HGCA recommended control thresholds to decide whether or not treatment is required.

These thresholds are based on plant population densities and have been developed from new understanding of the maximum number of buds a pollen beetle can destroy and the number of excess flowers produced by plants in varying populations. HGCA research showed that low population crops have more excess flowers, which can be sacrificed without yield loss, while high population crops have fewer.

Revised thresholds for winter and spring oilseed rape. (Source: HGCA Information Sheet 18/Spring 2013 ‘Monitoring and control of pollen beetle in oilseed rape’) are;

Plant Population per m2 Pollen beetle per plant
< 30 25
30 -50 18
50-70 11
>70 7

If numbers exceed thresholds, treatment with Biscaya will control even the most resistant pollen beetles. In recent trials yield responses from Biscaya have outperformed competitor treatments and ranged from 6.5% (under low beetle pressure) to 12.5% (under high beetle pressure) over untreated.

Flowering is rarely even across a field. Usually, by the time thresholds are breached some plants will have begun flowering but the field will not yet be flowering in earnest. Product choice is then limited (see diagram below) but there is still significant risk of crop damage.

A big practical advantage with Biscaya is that it can be used right up to the end of the damage susceptible period which is when around three quarters of the plants in a field have 20% of their flowers open. The latest time of application for most other treatments is GS59 yellow bud.

 

Pollen Beetle application: Latest times of application

diagram

Integrated Pest Management checklist – Winter oilseed rape

  1. Know your plant populations
  2. Monitor pollen beetle migration with Bayer Pollen Beetle Predictor
  3. When it indicates risk, assess beetle populations
  4. If thresholds are breached, apply Biscaya at 0.3 L/ha
  5. DO NOT apply insurance sprays

Click here to use Bayer Pollen Beetle Predictor

Click here to download HGCA Information Sheet 18 / Spring 2013