The trend to wider row spacings may be reversed, with work indicating that wider spacings in wheat and barley plantings in the SA's Mid North were not being rewarded with higher yields.

Site manager Peter Hooper said that this could be because there is more plant competition within the row, and so fewer heads produced.

"This may mean that lower seeding rates may have to be used," he said.

Timing of sowing is being tested with trials of staggered plantings.

University of Adelaide's Dr Glen MacDonald said that when you sow early, you sow into relatively long days. The wheat ear starts to form four to five weeks after sowing and the trigger to form is based on day length and temperature.

The varieties Correll and Frame have a genetic control to delay its development.

In contrast, Axe does not have a long requirement for cold weather, so it can be stimulated to progress to maturity quite early in the winter.

With regard to peas, as indicated by farmers attending, there was also a move to sow them earlier.

The fourth week of May was shown to be a popular choice.

South Australian Research & Development Institute's Larn McMurray said the computer model 'Black Spot Manager' indicated early June was the preferred sowing time, to avoid black spot spores.

However, most farmers did not feel confident to go that late with this year's early break.

Results indicate that seed treatment P-Pickle T only lasts six to eight weeks, with plants being susceptible to rain outside that period. Use of the fungicide Mancozeb does not give full control but does suppress foliar levels, especially when you can get a spray down into the plants at the 9 - 10 node stage.

A second spray should follow at 13- 14 nodes or two to three weeks later and definitely before a rain. Mindful of economics, Mr McMurray suggested that Mancozeb was still an option in high yielding crops if spring turned wet.

New pea varieties to inspect on the Hart Field Site main field day on September 15 include OZP0602, which has been shown to have a longer flowering window and has the potential to set more pods. Mr McMurray said this does not always mean more yield, but certainly gives more opportunity.

* More on Hart in Stock Journal, August 27 issue.