New sugar beet economics make fungicides a vital investment

UK - June 28, 2006

Susceptibility to mildew means fungicides are a worthwhile investment on popular new rhizomania resistant sugar beet varieties, especially under the new price regime says Dow AgroSciences. 

Brooms Barn Beet Research Centre trials show that even in low disease seasons a fungicide spray delivers a 4 t/ha boost to average yields.  “At 2006 prices this is worth £108/ha demonstrating that the economics of fungicide inputs in sugar beet have changed sharply for the better this year,” explains Liz Tomkinson, regional business manager at Dow AgroSciences. 

Many growers are changing to the higher yielding rhizomania resistant varieties, which have low mildew resistance and in some cases a susceptibility to brown rust.   

“The highest yielding variety Palace has a rating of just 2 for mildew and 6 for rust.  The next three highest yielding varieties Justina, Miriam, and Salvador all have mildew ratings of 4 or less,” says Ms Tomkinson.  “Such ratings mean the new varieties have the potential to lose up to 25% yield from mildew infections, so agronomists will be recommending fungicides from mid July onwards. 

“Fortress (quinoxyfen) is a proven sugar beet fungicide which gives the longest lasting protection against mildew.  In independent trials Fortress, in tank-mix with a triazole, has consistently given the best value for money where there has been moderate to severe mildew and rust infections.” 

Dow AgroSciences recommends a first spray of Fortress at 0.15 l/ha with cyproconazole at 0.125 l/ha in mid-July on moderately mildew susceptible varieties, rising to 0.2 l/ha on more susceptible varieties.  A second spray using Fortress at 0.15 l/ha plus cyproconazole can be applied up to four weeks before harvest.  Where rust is less of a problem use Fortress in tank mix with carbendazim + flusilazole at half rate. 

“A second spray is justified on those high output varieties that show low resistance to both mildew and rust, providing sufficient persistence and value for money to cover the last growth period, particularly on late lifted varieties,” advises Ms Tomkinson.