HC 668 Insects and Insecticides

Written evidence submitted by Richard Cartwright (CCC Independent
Agronomy Services)

Cereals (Winter Wheat, Winter Barley and Winter Oats)

All winter cereals can be badly affected by Barley Yellow Dwarf Virus (BYDV).

Winter Oats are most severely affected , followed by winter barley and wheat . All lose yield and grain quality . Early drilled crops are worst affected and severe cases can result in near total write off of the crop . This is an aphid transmitted virus which is spread over the autumn and winter period by two aphid vectors, the Bird Cherry and Grain aphid. Late drilled crops from mid October are largely free of the virus but will lose approximately 2 to 3 t/ha yield of potential yield due to later than optimum sowing dates .

Clothianidin (trade name Secur or Deter ) is a very effective seed treatment for controlling all species of virus vector aphids . The aphicide remains active in the crop for up to 10 weeks from emergence but the persistence is dependent on drilling date, seed rate and speed of crop growth.

Before the neonics were available, pyrethroid insecticides were sprayed on the crop . In high risk areas in the south this was usually done twice . However in the past couple of years the Grain aphid has become resistant to pyrethroids .

IF NEONICS WERE BANNED ON CEREALS, THERE COULD BE DISASTEROUS CONSEQUENCES AS FARMERS WOULD BE FORCED TO USE REPEATED APPLICATIONS OF CHLORPYRIFOS (an organo-phosphate aphicide) ON A VERY WIDE SCALE ON CEREALS IN THE AUTUMN TO CONTROL BYDV.

Oilseed rape (OSR)

OSR is attacked in the autumn by cabbage stem flea beetle and aphids .Yields can in the most severe cases be reduced by approximately 25%.

Flea beetle can severely damage crop establishment but could be controlled by pyrethroids . However repeated applications of pyrethroids at the very early stage of crop growth are likely to be needed if neonics were banned .

Pyrethroids would NOT provide any control of Myzus persicae (which transmits Turnip Yellows Virus) as these aphids are almost entirely resistant .

THERE WOULD BE NO MEANS AT PRESENT TO CONTROL TURNIP YELLOWS VIRUS IN OIL SEED RAPE  WITHOUT NEONIC SEED TREATMENTS.

THE SAME SITUATION WOULD BE TRUE IN SUGAR BEET AND FODDER BEET WHERE MYZUS PERSICAE TRANSMITS BEET WESTERN YELLOWS VIRUS.

When considering whether neonic seed treatments will affect bees foraging in the crop the following summer, it is important to consider the following:-

First, the seed is drilled in the Autumn when bees will not be foraging in the crop, and secondly the crop has a massive increase in green leaf production over the winter and spring before it becomes attractive to bees during the crop flowering stage, and the chemical concentration at this stage is likely to be very diluted.

Pollen Beetle feed on pollen in oilseed rape flower heads . Crops are susceptible to damage during the green bud stage . Pollen beetle are increasingly resistant to pyrethroid insecides BUT if Biscaya (Thiacloprid) was banned, alternatives are available in the form of Indoxacarb or pymetrozine.

5 February 2013

Prepared 18th February 2013