Our Vegetable Knowledge

Our Growers | The Young Family

Brothers Norman, Harvey and Ivan Young and their extended family crop around 200 hectares of carrots and potatoes near Raetihi in the central North Island....

Our Growers | McFarlanes Ag

Hamish McFarlane, runs a third generation, mixed farming operation just north of Temuka. There he grows raspberries, blackcurrants, potatoes, carrots, cereals and runs lambs for winter finishing alongside grazing cattle. A busy operation, Hamish values the strong technical support he receives from his local Fruitfed Supplies team.

Sclerotinia is a genus of fungi, closely related to Botrytis. There are many species, the most relevant in New Zealand vegetable cropping being S. sclerotiorum, and to some extent, S. minor.

S. sclerotiorum is a problem for lettuce, brassicas, legumes, carrots and solanaceous crops, although with 400+ known host species, many other crops are impacted. Once infected, plants exhibit white, fluffy growths (mycelium) that can spread directly between plants, eventually forming black, hardened sclerotia. It can spread aerially, via ascospores, and can survive for long periods in soil without a host via the sclerotia. 

Sclerotinia management requires direct control of the pathogen, minimising exposure to susceptible hosts, and avoiding conducive environments for the disease to develop.

Pathogen control:

• Machinery sanitation and removal of infected plants slows the spread of inoculum within and between paddocks.
• Application of effective fungicides and biofungicides registered for various crops to prevent infections or reduce their severity.
• Sclerotia survive poorly on the soil surface, so tillage strategies that leave them exposed can reduce pathogen loading over time. Conversely, deep inversion tillage can bury sclerotia out of range of the following crop.

Susceptible host:

• Destroying crop residues promptly after harvest minimises the “green bridge” that allows the pathogen to propagate.
• Appropriate nutrition and biostimulants improve crop resilience to stresses that can affect disease susceptibility.
• Effective weed management removes alternate hosts.

Conducive environment:

• Ascospores break down quicker with increased solar radiation. Managing weeds, plant density and vigour allows more sunlight to penetrate canopies.
• It also improves airflow, reducing local humidity and soil moisture, conditions that favour the disease.

For more information on products and strategies that can manage Sclerotinia in your crops, contact your local Fruitfed Supplies Technical Horticulture Representative