Leatherjackets – A pest of new & established grassland
Leatherjackets – A pest of new and established grassland Leatherjackets like similar conditions to slugs (cloddy seedbed) but can be more at home in very moist (or flooded) soils than slugs. Leatherjackets are generally not a major problem in cereals although incidences of attack are more common over the past few years. Commonly problems arise following leys or after heavy dressings of farm yard manure or where the field has a history of leatherjacket activity. Leatherjackets feed underground or just at the surface. Cutting the emerging or emerged shoot below soil level is common. Alternatively young leaves can be cut at the ground level. There are several signs that indicate the presence of leatherjackets: Large numbers of adult Crane flies in July and August Feeding by rooks, crows and starlings Bare patches appearing in the grass Adults lay eggs between July and September in grass and cereals Eggs hatch 2-3 weeks later and the larvae feed in mild spells during autumn to late spring, pupating in the soil late May-June 90% of the time adults stay and lay eggs near to where they emerge, causing the population to continue to increase in the same field if they are not dealt with. Leatherjackets feed on the roots and stems of grass plants at or below ground level. New leys – Reseeded leys can be completely destroyed by leatherjackets Established grassland – Leatherjacket feeding not only reduces yield, but can also lead to the destruction of large areas of fields. At the economic threshold of 1 million per hectare, the weight of leatherjackets feeding below ground can be greater than the weight of livestock above ground. Ploughing grassland in July and subsequent cultivations can destroy up to 50% of leatherjackets. Insecticide gives reliable, consistently high levels of control of leatherjackets. It is acknowledged as the standard treatment. The control achieved is such that dry matter yield can by increased by as much as 80%. Treatment with 1.5 L/ha before the first signs of damage could save the crop from months of feeding. This will increase the yield response considerably. Crops identified at risk should be sprayed at the earliest signs of damage. Avoid periods of prolonged frost as pests are less active. Temperatures above 5°C give best results as that are when leatherjackets are near the soil surface. Spray 1.5 L/ha in 200-1000 litres wa Leatherjacket sprays taken off the market Chemical companies have received notification from the Irish regulatory authorities (PCD) concerning the current approval for chlorpyrifos-ethyl containing products (sold in the Republic of Ireland under the trade name Dursban 4). This notification outlines the timelines for the managed withdrawal of all chlorpyrifos-ethyl containing products and including dates for usage, storage and disposal of the product.
Below please find the timelines concerning the withdrawal of Insecticides: Insecticides cannot be sold by distributors, wholesalers or retailers after the 31stMarch 2016. Growers cannot spray chemicals after the 31st March 2016. Chemicals can be stored by wholesalers/retailers and growers up to and including the 30th September 2016 to facilitate product recovery by companies. Chemicals that is one year old or less can be returned via the supply chain (retailers and wholesalers) if unopened and in good general condition. Chemicals that is older than one year and/or opened and/or considered in poor condition must be disposed of as hazardous waste at the expense of the person in possession of the product. What now? With the chemical option gone to control this pest we have to start looking at alternatives because these pests can devastate new leys if not controlled, but the risks can be avoided through effective cultivations and the use of brassica break crops. The use of fast–establishing hybrid brassicas (such as Swift or Redstart) or Maris Kestrel kale have the added benefits of providing an additional source of high quality grazing, reducing the effect of any forage shortfalls between leys. This can be timed to provide late summer, autumn or even winter grazing for cattle or sheep. Ploughing and cultivating in summer, and sowing a break crop, will disrupt the life cycle of the crane fly and is known to reduce leatherjacket populations by 50%. We need to be very aware of the threat from leatherjackets and be familiar with the obvious signs that they are present in your field and which will allow you get act fast and prevent sward damage. *Information in the above article were taken from Dow AgroSciences and Pitchcare.com websites. #Farming