Evaluating the impact of haulm destruction method on development of disease in seed potato crops


Since the withdrawal of sulphuric acid as an option for haulm destruction, seed potato growers have had to convert to other methods of haulm destruction.  These have included other chemical options, haulm pulverisation or a combination of chemical options and haulm pulverisation. One key concern where haulm pulverisation is used is the risk of spreading the blackleg bacterium, Pectobacterium atrosepticum (Pba), from affected plants to other plants within a crop and between crops.

The objectives of the project were:

  •  To evaluate the effect of different haulm destruction methods on disease development post-harvest in the seed crop situation.
  •  To evaluate a pre-haulm destruction treatment with a disinfectant to reduce inoculum on haulm and thereby spread to daughter tubers.
  •  To evaluate the spread of P. atrosepticum from blackleg plants to healthy plants as a result of different haulm destruction treatments.


Two replicated field trials in Aberdeenshire (Olmeldrum; Rothienorman); eight large-scale field comparisons; and trials to study the spread of P. atrosepticum inoculated into crops, were carried out during the project. Levels of Pba contamination of daughter tubers were measured in the trials.In some trials, a distinction was made as to whether Pba was present on the surface of tubers or in samples from the stolon end of peeled tubers. In the replicated field trials, the effectiveness of the haulm destruction treatments (foliage senescence and stem desiccation) was measured.Colonisation of stems by Phoma species (the fungi which cause gangrene) was assessed just prior to harvest and tuber disease (soft rot, gangrene, pit rot) was assessed in samples of stored tubers.


In all the large-scale field comparisons, where pulverisation was compared to chemical desiccation; and in the two replicated field trials where five haulm destruction programmes were compared, no differences in the tuber contamination of the periderm of daughter tubers by Pba was observed between the treatments.When compared to the haulm desiccant-only programme, those programmes involving pulverisation resulted in some significant reductions in pit rot incidence and severity in the trials. In these trials the non-flailing treatment was only diquat, consequently the effect of a diquat and carfentrazone ethyl treatment was not evaluated.
Project code:
R453, R431
01 April 2011 - 31 July 2012
AHDB sector cost:
Total project value:
Project leader:
Daan Kiezebrink


R453 Final Report R431 Final Report 2012

About this project

To identify the impact of haulm destruction method on disease risks in seed potato production