Does disease matter?
Many fields will be sown to grass this autumn. Those who buy the seed have much to consider but one thing that repeatedly gets overlooked is that of disease resistance for mildew, crown rust or Dreshlera. Resistance ratings for disease range from 3.8 to 8.1 so why choose a variety prone to infection?
Powdery mildew is a common and destructive disease. Actual yield losses depend on when the disease starts and its severity and has been conservatively calculated at 6%. Predicting loss is complicated because it depends upon several factors including climate, “the year”, cropping system, cultivar and plant nutrition.
Conservatively - if you loose circa 3.3% to each disease each time you cut that means you are down circa 10% on productivity.
Doing the maths
An average silage cut 8t/ha DM.
Three cuts per season
Grand total = 24 t DM /ha (or 21.6 t if we deduct 10%.)
With one 8 ha (20 ac) field producing a total of 172.8 t instead of 192 t or in round figures one 20 t load of something else that has to be purchased. Does it not make financial sense to look again at those disease ratings?