More than 15 million ha of grain crops such as cereals, oilseeds and legumes are planted each year in Australia making it one of its largest primary industries. However, while annual Australian grain exports are worth in excess of $6 billion, growers spend several hundred million dollars each year controlling invertebrate pests that attack emerging seedlings. In southern Australia, grain crops are grown in Mediterranean and temperate climatic regions with winter dominant rainfall. Seeding usually happens between late April and June. Cropping rotations differ between regions depending on the timing and reliability of autumn rain. Seedlings are the most vulnerable stage of crops with canola seedlings being the most at risk. Legume and cereal seedlings withstand pest damage better. Control costs, therefore, vary between crops. For all crops, factors such as depth of sowing, seedbed firmness and environmental conditions also affect establishment. Feeding by pests can cause plant death and/or result in poor plant stands. This in turn leads to increased weed competition, poor canopy structure, delayed flowering, lower yields and, in some cases, the need for complete resowing. While the recent shift to minimum or no tillage systems has helped to conserve soil moisture and reduce wind erosion and fuel costs, it has also led to changes in the types of pests in crops. Minimum tillage creates micro-environments that suit both pest and beneficial organisms. For instance, no tillage systems with stubble retention can favour slugs and snails. To avoid the need for pest monitoring and to protect small profit margins, growers often use prophylactic pesticide applications at sowing. But these broad-spectrum pesticides also kill beneficial species which could lead to secondary pests becoming an increasing problem. Broad spectrum pesticides also select for pesticide resistance in establishment pests. Redlegged earth mite, Halotydeus destructor, resistance in southern Western Australia is one warning sign of this. The main invertebrates attacking emerging grain crops include mites, lucerne flea, slugs and beetles.
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