Russet Burbank Growth Stages 2003

Our most forward crops of Russet Burbank are now meeting across the rows and have tubers around 20mm in diameters.



These forward crops can now receive their remaining nitrogen and it is safe to commence irrigation regimes within the next week.



For crops which are not so advanced it is recommended that irrigation and nitrogen

top dressings are delayed.



It is possible that either input, applied too early, could exacerbate the internal browning disorder to which Russet Burbank is prone.



Action



Delay nitrogen top dressings and the commencement of irrigation programs where crops have not yet reached the stage where tubers are at least 25mm in diameter.



All Russet Burbank Crops



It is essential to maintain short interval blight sprays now and throughout the season on Russet Burbank.



For product choices see our web site.



The key to successful blight control will be to maintain protection at all times. This will best be achieved by maintaining short intervals. Choosing products which have complementary actions and constructing sequences accordingly will assist in keeping blight at bay.



With minimum temperatures now well above 10�C and hot humid conditions prevailing with localised rain fall, conditions for the development and spread of blight are becoming increasingly risky.



Aphids



There is an association, for the variety Russet Burbank, between the disorder of net necrosis and direct aphid feeding damage. It is prudent therefore to regard the variety as of higher risk when assessing aphid numbers and be prepared to apply an aphicide when aphid numbers are seen to be increasing in the crop.



Action



Monitor canopies for influxes of aphids and make a careful check of predator numbers.



Typical predators would be ladybirds and lacewings together with signs of parasitised aphids, indicating the presence of predatory wasps.



With aphid numbers increasing and the presence of winged aphids in many crops indicating more movement, it is essential to be aware of increasing aphid populations in crops and to take action accordingly. Use an insecticide which will preserve predator numbers and thus prevent unnecessary additional sprays.