Beetroot Leaf Spot

Latest Update 16th November 2014.

Beetroot leaf spot
  • Binomial name:                                       Cercospora beticola.
  • Family:                                                   Mycosphaerellaceae.
Notes.
  • Beetroot leaf spot is a fungal plant pathogen which typically infects plants of the genus Beta.  It not only infests Beetroot, it also attacks Silverbeet, Spinach and Sugarbeet.
  • Cercospora beticola survives in infected crop residues. The fungal spores overwinter on decaying leaves on or in the soil, and quickly establish themselves on new crops in the following season.
Why Beetroot Leaf Spot is a Pest.
  • Leaf spot disease caused by Cercospora beticola is the most destructive foliar pathogen of sugarbeet worldwide.  In addition to reducing yield and quality of sugarbeet, farmers spend large sums of money on fungicides to try to keep the pest under control.
  • In the home garden, similar problems can effect all the beet crops, and in the organic garden, care and vigilance are most important if good quality crops are to be harvested.
Organic Pest Control.
  • A four year crop rotation is the best control of Beetroot leaf spot since the fungal spores don't survive without a host plant for more than about 2 years.
  • The biggest problem for organic gardeners seems to be the compost heap.  Care must be taken not to add infested plant tissue to a compost heap unless you are completely confident it will kill the Beta plant pathogens by achieving temperatures above 60 deg C (see hot composting).
  • A drench of aerated compost extract and generous top dressings of homemade compost before each new crop is sown, will boost microbe activity in the soil.  As a result natural predators help keep the Cercospora beticola under control.
  • Regular monthly foliar spraying of aerated compost tea boosts microbial activity and controls leaf spot by occupying all the available leaf surfaces in the plants phyllosphere.