From the President’s desk
Summer is upon us. Despite forecasts, in Mudgee we’ve received no significant rain for two months, with bouts of three to four days in the low to mid 30s, often with strong wind that sucks the moisture out of leaves. We learned several years ago to water water water and not trust the weather forecast, after experiencing massive catkin drop in an abnormally hot late March. Most nights are cool and still- allowing our 3000 grove trees to recover. High early morning humidity, warmth and young plant tissue wounded by buffeting strong winds create ideal conditions for infection by Bacterial Blight.
HGA obtained a Minor Use Permit for Cupric Hydroxide earlier this year. The permit recommends spraying during leaf fall and when the tree is dormant. Copper sprayed on leaves can result in leaf scorch particularly on hot days and it is likely that some cultivars will be more sensitive than others. The permit suggests that growers considering spraying Cupric Hydroxide when trees are in leaf first conduct a trial spray on small number of each cultivar and observe for any negative effects. Cupric Hydroxide is known to cause less leaf scorch than Copper Oxychloride, other
advantages are it has a more active formulation, and leaves less residual copper in the soil. If HGA wishes to broaden the recommended use patterns to include full canopy, HGA need supply APVMA with data from trials on different cultivars in different climatic zones, ideally involving Departments of Agriculture or Horticulture. If you would like to assist these trials please contact HGA. Should you decide apply Cupric Hydroxide on trees in leaf, record the concentration of chemical and adjuvants (eg petroleum oils), air temperature and humidity at spray and post
spray, and the cultivars you sprayed. Should you see evidence of phyto-toxicity please advise HGA. Page 27, September 2012 issue of the Australian Nutgrower Journal contains an excellent article on how copper sprays work, and the effect of wind, rain and water pH on persistence and activity. The complete version of Prime Fact 257 can be found at www.dpi.nsw.gov.au.
HUES OF GREEN
For a number of years our trees appeared to be struggling. We have increased the amount and frequency of watering and delivered Nutri-soil (late August), Sea-sol (September) and three split deliveries of nitrogen (calcium nitrate) by fertigation. We have yet to deliver boron as a foliar spray. After I had done a test spray, we brought in a contractor to mist spray cupric hydroxide, and mixed it with petroleum oil at insecticidal concentration for
scale insect. Our trees have never looked better, we have nuts, vigorous new growth and the colour of mature hazel leaves is just on the blue side of the green spectrum. During the conference we visited a grove about the same age as our own managed under organic principles. It is pitched on a steep hillside in a high rainfall area, and maintains a
2 sward of grass and clover to the tree butt to mitigate wind and water erosion. The trees are a similar age to our own. Clem spotted that leaf colour was just on the yellow side of green, and that trees on the more exposed slopes were less vigorous than those in the lee of the hill. Two factors were at play. The owner relied on clover to provide nitrogen and was not fertilizing. Following the massive improvement we’ve seen in our trees I suggested he apply an organic source of nitrogen through the watering system and split the annual requirement into a number of small doses timed to coincide with peak need. Annual nitrogen requirements and split applications are discussed in the Hazelnut Growers Handbook. The other factor was exposure to wind. Keynote speaker at the conference, Professor David
McNeil, Tasmanian Institute of Agriculture, spent many years in New Zealand, working with hazelnuts on the Canterbury Plains, South Island, where groves are protected by high dense windbreaks. Prof McNeil explained trees are programmed to reach for light. Plant growth is governed by auxins (plant hormones). Auxins produced by the apical bud gravitate down the stem and suppress the growth of side shoots. This ensures the plants investment and that highest bud
grows fastest. Other stem auxins respond to light by moving to the shaded side of the stem which grows faster, ensuring growth is always in the direction of light. Apart from physical damage, constant buffeting by wind shifts the relative position of buds and stems, and disrupts the flow of auxins. Prof McNeil said a plant can become so confused
that it shuts down its stomata, ceases transpiration and photosynthesis and stops growing. Prof McNeil said windbreaks provide essential wind protection for hazelnuts, and that once planted it is false economy not to irrigate them.
It looks like I will be filling in the gaps in our windbreaks over the Christmas break. Most of the cold tolerant cultivars we planted cannot handle our very hard winter frosts. Casuarinas have been our greatest success. Avoid trees that are known to harbor borers. Don’t forget – January is the month to pick leaves for leaf analysis. Pick 100 mature leaves with the petiole at random through the grove, place in a paper bag so that the leaves dry out rather than rot, and send to a reputable laboratory. The results will guide your nutritional program for the following two years.
Clem and I wish you a Merry Christmas and a prosperous New Year.