The Tasmanian potato industry has thrived since the early 1900s, relying on the staple potato varieties of Up to Date, Kennebec and Russell Burbank to supply the ware and processor markets.

Early pioneers recognised that the development of quality seed potatoes depended on isolation and established the Tewkesbury Agricultural Station in 1934. At an altitude of 600m, the theory was that insects such as aphids would not survive the cold environment.

At its height, Tasmanian seed potato growers numbered around 150, many of whom were small landholders that also had other agricultural pursuits such as dairy. Seed certification began in the 1930s, with the aim to check the health of the crop and the occurrence of pest, virus and disease. Today, the state is still free of potato cyst nematode.

The perfect potato will meet the needs of the grower and satisfy the demands of the user (processor or consumer). In essence, the perfect potato is dependent on the quality of the seed potato, and crop management.

Suitable ‘clean’ land in Tasmania for seed potatoes needs to have been unused by other agricultural systems for several years, have good drainage and freedom from soil borne diseases.

“Tasmania is fortunate to be isolated from many potato pests and diseases, such as tomato potato psyllid,” says Frank Mulcahy, affectionally referred to in the potato industry as the Spud Doctor.

“Common scab used to be a major cause of seed potato rejection, anything up to 25 percent of the crop, but we rarely see that today. That is in part because of improved crop management, and seed testing and certification.”

As a seed certifier for many years, Frank has welcomed the improved testing systems that are now available, such as PredictaPT, to determine the levels of soil borne disease pathogens.

“Years ago, the buffer used to be around 30 percent seed rejection to ensure we had enough good seed, but with improvements in testing, that is nearer to two percent.”

“For the processors, all seed potato grower sites are to be tested – it’s not good business sense to lose 30 percent of your seed potatoes.”

If a seed potato crop is looking poor, it can be grown out to be potatoes for processing, Frank explained.

“With the benefit of data, I was able to show growers that by planting later and harvesting earlier, the rejection rate was significantly reduced,” he said.

“This is because the plants were not under as much stress from the cold weather that still occurs in October, increasing the rate of common scab. That data showed that early planting had a 60 percent rejection rate, compared to six percent if it was planted in early December.”

Testing techniques such as PredictaPT have increased the awareness for growers of the existence and prevalence of diseases such as powdery scab. A project that Frank worked on for a number of years conducted DNA mapping using GPS locations, with the view to using biofumigants to lower the presence of soil borne diseases.

While the use of biofumigants was not particularly useful, the associated testing did reveal that poppies and pyrethrum, common crops in Tasmania, are hosts for powdery scab, thereby affecting how crop rotations are conducted in relation to seed potatoes.

The advent of minitubers

The development of minitubers for seed potatoes heralded an advancement in the production and certification of seed potatoes. In the 1990s Frank worked with Technico, which developed the Technituber technology that changed how developing potato growing countries fared.

During Frank’s tenure with Technico, the concept of minitubers was introduced to countries such as India, Iran and Algeria. The focus was to ‘put the wheels of seed potatoes into those countries so they could establish their own seed potato industry’.

“When I started introducing minitubers to India, the country produced about 18 million tonnes of potatoes using government supplied seed potatoes that were easily generation seven or eight,” Frank said.

“With the introduction of minitubers, production is now around 50 million tonnes. While the introduction of quality seed certainly improved productivity, we also worked with the local elders to improve crop management.

“A lot of Indian potato growers operate on a few acres – one acre of rice, one acre of potato. A good farmer could achieve 10t/acre, the worst about 6t/acre. With good seed alone, the worst farmer could achieve about 8t/acre – the good farmer with better management could increase to 13-14t/acre.”

What it demonstrated is that good quality seed potatoes and tubers are only part of the equation.

Frank has spent much of his career communicating his knowledge through extension to guide growers to improve their seed potato yields.

“Soil management, plant health and nutrition, water and drainage, and integrated pest management are the basics that will improve a good farmer and make a poor farmer better,” Frank said.

“Testing through PredictaPT will guide the grower on what is going on in their soil. By doing that, Tasmania has stayed on top of site selection for minimal crop risk.”

As a boy of Irish heritage growing his first potato crop at 16, there is nothing more satisfying for Frank than walking through a potato crop at sunset to see the plants bounce back from the day’s stresses, looking green and healthy.

As the Spud Doctor and in Frank’s legacy as a seed certifier and tester and minituber pioneer, that love of the humble potato has served the Tasmanian industry well.