RUSSET BURBANK GROWERS

<b>Russet Burbank Growers</b>



Crop growth has been excellent since planting in April and most crops now have a complete canopy and are initiating tubers.



Management of Russet Burbank crops at this stage will focus on nitrogen inputs; blight control and irrigation.



<b>Nitrogen Application</b>



For most varieties and most markets, nitrogen applications would be concluded with an application at Tuber Initiation. For Russet Burbank there is some evidence to suggest that it is worthwhile delaying this final application until the tubers are 30-40mm in size.



<i>Action</i>



&#61485; Total nitrogen application, at Index 0, should be 180-200kg/ha.

&#61485; The final topdressing, if a balance is required, should be applied when average tuber size is 30-40mm.



The reason for delay is to prevent or reduce a �brown centre� disorder that Burbank can occasionally be susceptible to. Applying the balance of nitrogen applications too early is suspected to exacerbate this problem.



<b>Irrigation</b>



Just as early Nitrogen topdressing could be a problem, it is also suggested that irrigating too early could contribute to the brown centre disorder.



Normally, for processing varieties, irrigation for yield would commence when tubers are well developed and critical SMD�s are approached.



Critical SMD�s are determined largely by soil texture (which determines water holding capacity) and range from 40mm on sands up to 60mm or greater on silts or clays.



<i>Action</i>



&#61485; The first irrigation on Burbank should be timed as normal but should apply only 15mm as opposed to the more usual 25mm.

&#61485; Full rate irrigation should be delayed until tubers have reached 25-30mm.



<b>Blight Control</b>



As a high risk variety maintain short intervals, irrespective of product.



Now that canopies have closed, systemic products are no longer worthwhile. The programme should now involve sequences of products such as Tanos, Shirlan, Invader, Curzate etc. See Newsletter number 34 for a full description of products.



There is useful information on weather, Smith periods and other aspects of potato blight on the web. Try www.potatocrop.com or www.syngentapotato.co.uk.



<b>Aphid Control</b>



Aphid numbers are low at the moment and predator numbers are generally high. There is no current need to treat.



<i>Action</i>



&#61485; Monitor numbers and, if treatment is necessary, use a product such as Aphox or Plenum which will preserve predator numbers.









<b>These Notes are guidelines only. The final decision rests with the user and Higgins Agriculture Limited will not be held responsible for any damage which may occur.

When using agrochemicals always read the product label and comply with its conditions of use.</b>