The effective management of a range of insect pests which target dairy farm pastures can help avoid economic loss in the form of damaged plants, wasted pesticides and the absence of beneficial insects. The correct identification of insect pests enables farmers to implement strategies to limit their ability to thrive and damage crop yield.
African black beetle
African black beetle is emerging as a major pest in dairy pastures, especially in ryegrasses, paspalum, kikuyu and phalaris. It’s often mistaken for other scarabs, so remember to double check you actually have African black beetle on your farm before taking action. In response to this pest, consider the use of insecticide treated seed when renewing pastures or chemical options registered for African black beetle control in grass and broadleaf pastures.
High numbers of armyworms can cause significant damage and rapid loss of vegetation in annual and perennial dairy pastures. The three species of armyworms are difficult to distinguish apart, however, correct identification in the field is generally not critical because their habits, type of damage and control are similar. There are several insecticides registered to control armyworm caterpillars and good spray penetration in the canopy is necessary for effective control.
Australia’s major mite pests are the redlegged earth mite, blue oat mite, balaustium mite and bryobia mite. The brown wheat mite and two-spotted mite are also considered important pests but their impacts are sporadic. Some mites are highly tolerant of pesticides so it’s important to correctly identify what mite you are dealing with when planning the best control method.
Blackheaded cockchafer grubs feed on clovers, ryegrass and animal dung and have even been known to consume young wheat crops. Often both the red and black-headed pasture cockchafers are present the same time in the same paddock, so accurate identification is essential. Unlike the redheaded cockchafer, the blackheaded cockchafer can be controlled by insecticides as they are surface feeders.
Redheaded cockchafer grubs live below the ground surface, feeding on organic and root material in the top 100mm of soil. When many larvae are present, pasture root systems are cut about 25mm below the soil surface. There are no known preventative management options and currently no insecticides registered for the control of redheaded pasture cockchafers. The underground feeding habit of the larvae gives them cover from insecticides.
Lucerne flea are pests of all broadacre grain crops and pastures but broadleaf plants such as clovers and lucerne are particularly susceptible to attack. Pastures are most susceptible at plant emergence when lucerne fleas move up plants from ground level, eating tissue from the underside of foliage. Monitoring is the key to reducing the impact of lucerne flea and pastures should be regularly monitored for damage from autumn through to spring.
Slugs and snails
The early detection of slugs and snails prior to seeding is ideal as there are increased control options available. Grazing in summer may reduce the number of slugs and snails by trampling and destroying their refuges prior to resowing. However, once a pasture has been sown and germination has commenced, control options are limited to baiting.