Brett Rosenzweig Industry Development Officer In The Orchard
Now the 2011/12 season is nearly over, here are a few suggestions to help prepare for the next...
Soil Salinity and pH. Even after receiving above average rainfall for the past two seasons, it’s still worth the effort to take soil samples for salinity and pH analysis. For sprinkler irrigated orchards, samples should be taken from approximately 30, 60 and 90 cm (within the average wetted area of the sprinkler pattern) or at closer intervals if your soil depth is shallower than 1m. While salinity levels should be low after two years of above average rainfall, it is still beneficial to target known salinity hotspots from previous years or known drainage areas where water tables may have risen and consequently brought salt into or close to the rootzone. The same principle applies for drip irrigated orchards, however sample at 20cm from the dripper (in the wetted area of the dripper) and 60cm from the dripper (the edge of the wetted area of the dripper). High salinity levels 60cm from the dripper could lead to uptake of salt by the tree after light rainfall events as the salt is pushed back into the rootzone. pH should also be analysed in addition to salinity, particularly in drip irrigated orchards and those orchards with high ammonium nitrogenous fertiliser inputs. Annual soil analysis for pH will allow you to build a database of results that will indicate whether any alarming trends are occurring. It is still not too late to take soil samples for analysis despite the lateness of the season. Next season’s water allocations are expected to be 100% so if soil salinity problems exist, a timely leaching irrigation
and other micro nutrients (e.g. Boron and Zinc). Rates for Lo-Bi Urea are usually 1% or 10kg/1000L. Refer to Fact Sheet 02.
could be applied to take
Disease pressure. This season has again seen conditions suitable for the development of rust, particularly in late summer, when spore populations have reached their peak and control options have been limited due to withholding periods. It is crucial to achieve 100% defoliation this winter to stop overwintering and carryover of rust spores into next season, the primary source of inocolum. Even if the tree is mostly defoliated it is
advantage of any unused allocation from this season. Soil samples can be taken and analysed up to the beginning of July, before any profile building irrigations commence. Refer to Fact Sheet 09. Post Harvest. Post harvest fertiliser should have been applied by now. If leaf retention is good, consider the application of “bud building” sprays using Lo-Bi Urea
Figure 1: Increase in rust spore population with optimum growing conditions