Farmers get a good pre-season knockdown

While some farmers did miss out, for many summer rainfall was the best it's been in many years, resulting in a significant amount of winter weeds - ryegrass, wild radish, capeweed, barley grass and brome grass - to germinate and subsequently be killed.

Usually growers would be spraying summer weeds for moisture and nitrogen conservation and while that is definitely still useful, they've also been able to get a kill on the major problem weeds that are a winter issue.

Independent agronomist Michael Lamond said growers were aware that they have to use fairly robust rates of good quality products to ensure they get a kill, however getting that knockdown had its challenges.

"For example, the balance this year was whether to let weeds like ryegrass get an extra leaf or two before spraying to get more product in or spray at an earlier growth stage before the forecast heat set in," Mr Lamond said.

"For some of the difficult to control weeds, the results have been a bit variable due to the weed size at spraying and the timing of hot days before and during spraying.

"In some cases where growers went early they didn't get the kill they expected due to lack of coverage, while in some other instances where they delayed a little and got a bigger weed, it has resulted in improved weed control, even though there were hot days before and during spraying."

Some growers had to go back and spray twice to get a complete kill on difficult to control weeds but in general it has gone really well.

In the majority of the grainbelt the green bridge has been eliminated, removing the food source for nasty insects such as green peach aphid, diamondback moth and redlegged earth mite, which in some cases have developed levels of resistance to insecticides.

As a result, growers have reduced the numbers of insects around that could cause early infection when crops come up.

"With the next rainfall event, there will be a lot of canola sown dry - when the surface dries out enough and if there is an early rainfall event to get the canola up, the emerging seedlings will be at risk of damage from green peach aphid," Mr Lamond said.

"In Esperance a couple of years ago, where there was early sown canola, growers in the higher rainfall regions close to the coast left country unsprayed for stock feed and as a result struggled to control the early infection in green, young canola plants.

"By getting rid of the green bridge we're going to significantly reduce the population of green peach aphid and the risk of young canola getting severely damaged by the pest."

Out in Bencubbin, the Sachse family completed its sixth and final week of spraying last Friday, just in time for the Easter break.

Ben Sachse, who helps co-ordinate the 8000 hectare cropping program alongside his parents Tony and Margo, said they had really good summer rainfall.

"We had 70 milimetres at the start of the second week of February which germinated all the summer weeds," Mr Sachse said.

"Then, just when we only had a few days of spraying left we received another 90mm in the first week of March - both of those rains were really steady and soaked in well.

"Obviously we had to stop spraying for a week until everything dried out and until the winter weeds came up, then we had to start all over again, so most of our cropping program has seen a second knockdown spray."

On top of allowing for a second knockdown which will help with weed and insect control, the amount of summer rain is likely to have a huge effect on barley crops across WA by limiting levels of spot type net blotch infection.

In previous years when there has been several days of rain in a row and cool temperatures for two or three days, there has been a significant subsequent release of spot type net blotch inoculum from barley stubbles.

However, as the green bridge has been killed, when the inoculum is released, there is no host for it to latch onto.

"History tells us that when we have these conditions we don't have the severe early infection of emerging barley seedlings when sown into unburnt barley stubble," Mr Lamond said.

"It is likely the inoculum levels or loading in barley stubble for spot type net blotch is not going to be anywhere near as high as it is in a year when you don't get summer rain.

"We know from experience that when you get a few days of rain with cooler temperatures, the inoculum released from the barley stubble is significant which means the loading that is there to infect young barley plants when winter comes is going to be significantly less."

That means growers who are going to go barley-on-barley and habitually burn their barley stubble, probably don't need to do this year and there also shouldn't be much of a need to use a seed dressing.

However, that might not be the case for everyone - for growers in regions where there was less rain and less cool days, the impact on reduced early inoculum levels will not be as significant.

By having that rainfall event and getting that inoculum spore released, then spraying the green bridge and getting a good knockdown, the inoculum is lost as there is no host for it.

With spraying complete, growers are turning their focus to seeding and Mr Lamond predicts there will be a lot of crops going into the ground earlier than normal.

"Generally growers will sow 60-80pc of their program dry and only leave a bit for later on, but there might not be a need to leave so much out because there has already been a germination," he said.

On top of spraying and trying to get good control, the Sachses were also trying to put a dent into their liming program at the same time.

"We haven't had a lot of time to think about seeding yet, but we will start seeding in mid-April," Ben said.

"I think lupins, canola or oats will be seeded first and after all this summer rain, it could be the year for canola."