Using Fazor (maleic hydrazide) on potato crops in the field around five weeks to harvest is suggested to be a good start as it helps suppress sprouting in store and will reduce volunteer potatoes in next year’s crop.
Dow AgroSciences has been investing in Fazor in the last two years, not only to investigate its volunteer potato efficacy but also to demonstrate its sprout suppression capability.
In 2010 trials were laid down testing nine contemporary potato varieties including Maris Piper, Estima, Lady Rosetta, Saturna, Markies, Hermes, Russett Burbank, King Edward and Cara. Fazor was applied in the field according to its label recommendation; harvested potato tubers were stored and evaluated for sprouting over a one year period.
Small tubers, representative of chats and the cause of volunteer potatoes, were subsequently re-planted and assessments made for levels of volunteers arising the following year. Tubers were tested for quality and, whilst a small increase in dry matter was observed overall, fry colour and fry rejects were unaffected and were commercially acceptable for all tested varieties.
The trials demonstrated that Fazor significantly reduced sprouting in all varieties, with shoot suppression being between 83 and 95% for all varieties 12 months following treatment. When tubers from the treated crops were then planted, Fazor gave excellent reduction in volunteers, with levels of control of being between 97 and 100%. The trials also confirmed that residue levels were low and stable over the year of storage and well below the MRL of 50mg/kg.
Alex Nichols of Dow AgroSciences says that this research work has confirmed that Fazor used on a range of contemporary potato varieties delivered exceptional suppression of volunteers and sprouting in store, with no detrimental effects on the crop or on processing quality.
He advises growers to plan an integrated programme for both sprout suppression in store and for minimising volunteer potatoes left behind from the previous year’s crop. This should begin with an in-crop application of Fazor. “The timing and conditions of application for Fazor need to be spot on for best results. Although I can’t say we have ever had to contend with such extremes as we are seeing now, I would advise going back to basics to make sure that the key application criteria are met. The effectiveness of Fazor is a function of application timing, growing conditions at application, accuracy of application, variety and storage conditions.”
“In terms of application timing, growers should calculate back at least three and ideally about five weeks from intended burn down date. This allows the chemical sufficient time to be taken up by the leaves and translocated to the tubers where it acts. The crop should be actively growing and the haulm mostly green, but with a few of the lower leaves turning yellow and, where relevant, most of the flowers fallen.”
“This could be a challenge this year as prolonged planting dates, some replanted crops and the weather may mean that there will be a range of growth stages. Each field should be checked for maturity and tuber size, using test digs. The guidelines are that the smallest tubers required to reach marketable size should be greater than 25 mm across.”
The most difficult condition of application this year is that crops should not be stressed by drought, pests, diseases, high temperatures (in excess of 26ºC) or water logged. “Certainly drought and high temperatures should not be an issue, but unfortunately some may suffer from water logging this year."
LISTEN: http://cpa.ds.npr.org/nwpr/audio/2012/08/POTATO_DISEASE.mp3
