- Shifting the growing season to help control weeds. Sowing in spring will allow more knockdown herbicides to control weeds such as annual ryegrass, and less reliance on selective herbicides.
- Spread workload. A two month delay in sowing will delay harvest by one month.
- Possibility of selective herbicides working better. Cold and frosty weather stresses weeds and crops. Spring sown crops should provide ideal conditions for herbicide application.
- Generally lower average yields than winter crops, but could be higher in some seasons.
- Some extra costs in seed, insect and disease control. Could be offset by lower fertilser and herbicide costs.
- Up seeding rates. A rule of thumb for winter crops is to raise plant establishment targets by 5 plants/m2 for every week delay in sowing. For example a May sown crop may require 140 plants/m2, planting four months later in September and populations of 220 p/m2 might be more suitable.
- If planting wheat, use a stem rust tolerant variety. Stem rust is a much bigger problem as temperature increases. I have heard that stem rust is only active once the average daily temperature exceeds 18 degrees. For Southern Victoria this occurs in December when May sown wheat is normally mature, so stem rust won't be as big a problem in early sown crops as it is in late sown crops.
- Be on the ball. A May sown canola crop will be ready to windrow 6 months later in November. Canola sown in September was ready to windrow in January, only 4 months later. Everything happens quicker, have chemicals ready, machinery seviced and be ready.
- Be vigilent for insects. We lost quite a bit of barley to caterpillers, which normally do very little damage. Warmer temperatures increases insect activity.
When planting winter crops, beginning in April, it is advisable to plant the paddocks with the heaviest stubble and/or lowest weed burdens first. As the days get shorter, colder and wetter; lighter stubbles will be easiest to sow. When coming out of the winter, lighter stubbles will be ready to sow first. The heaviest stubbles will be the best for summer crops.
In 2011 we sowed a lot of crop in September, fortunately the weather for grain fill was cool, however in most years this would not be the case. Based on past experience, July and August sown crops will do ok. If it was September before you could get on a paddock I would consider waiting until it warms up and planting a summer crop. It would be interesting to see some modelling on this.