Brett Rosenzweig - Industry Development Officer In The Orchard
The 2012/13 season is drawing to a close; here are a few suggestions to consider over dormancy
Soil testing Post harvest is a good time to consider your soil testing needs. Soil testing can range from a simple salinity and pH test through to a full soil nutrition test. With sprinkler irrigated orchards take samples from multiple depths within the rootzone, in representative areas of the sprinkler wetted area and in representative areas of the orchard or known trouble spots. Sampling in drip irrigated orchards should be done within and on the edge of the wetted area in representative locations of the orchard. Refer to Fact Sheet 09. Soil nutrient sampling is a good indicator for any nutritional imbalances in the soil. All nutritional elements need to be balanced for good soil health and to optimise availability. If one element is highly disproportional to another, a deficiency can result. For more information about soil nutrient interactions, use the following link to go to a brief explanation of Mulder’s Chart. http://www.apal.com. au/site/DefaultSite/filesystem/documents/ APAL%20PLANT%20NUTRIENT%20 INTERACTIONS%20July%2008.pdf Post Harvest sprays Post harvest defoliation sprays should have started now. Either Urea or Zinc Sulphate is commonly used at rates of 5-7% and 25-28kg/Ha respectively. Leaf retention was generally good across the industry in 2012/13 and this is likely to cause a later and slower defoliation, even in the presence of a defoliant spray. Please ensure all leaves are off prior to the dormant oil spray to ensure adequate coverage, otherwise the oil will not be effective. I also talk below about the importance of a thorough defoliation and disease management. Disease pressure The past season has been very kind in regards to disease control with isolated reports of rust symptoms during flowering/ early leaf out. There was an occurrence of bacterial spot in Price and to a lesser extent other varieties in late spring/early summer. Otherwise the season was largely
If you don’t already, it may pay to apply a copper spray following defoliation. A winter dormant application of copper in addition to the usual pink bud copper spray may help fungal and bacterial disease management next season i.e. Bacterial Spot. Figure 2 indicates how maintaining good rust control can keep the spore population
disease free. There have been a number of comments about how much leaf cover was retained after harvest in comparison to previous seasons. Even though the almond industry experienced a disease free and dry spring, it is important to make sure there is no carryover of leaves and potential disease spores to next season. I refer to last autumn’s In The Orchard article...”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 still critical to apply a defoliation spray to remove ALL the leaves”. I’ve presented again the figures and table from the autumn 2012 article to highlight the importance and cost effectiveness of good winter sanitation of fungal diseases and how good control early in the season is vital.
Figure 1: Increase in rust spore population with optimum growing conditions
Figure 2: Incidence of rust in early season versus mid season