2 spore trapping
3 modelling the development of the crop
- Closely watch the lower leaves of crops during and towards the end of the rapid growth stage and expansion of the primary stem
- We have little objective information on which varieties are most susceptible but lots of anecdotal information. Markies appears one of the worst varieties followed closely by Estima and Saturna. Other varieties to watch out for are Cultra, Hermes, Lady Rosetta, Maris Piper, Mimi and Russet Burbank.
- Make sure that you have symptoms checked out by a competent lab. Alternaria alternata causes similar symptoms but is less agressive. There are several other foliage diseases, which can complicate the picture especially late in the season, when the foliage is less tidy. Examples are grey mould (Botryotinia fuckeliana), white mould (Sclerotinia sclerotiorum) and Verticillium wilt (Verticillium dahliae)