Pests & Diseases

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Potatoes Diseases

Bacterial breakdown in washed potatoes

Bacterial breakdown is a significant problem in washed potatoes throughout Australia. This disease is caused by three species of Erwinia, which rots potatoes in the field and in storage.

Potato tubers have a higher potential risk of forming bacterial soft rot immediately after major handling steps such as harvest, washing and cutting seed pieces. Washing in particular has been associated with outbreaks of the disease and in South Australia rotting of washed tubers after packaging has caused major losses. Many potato washing sheds in South Australia use recycled water for the main washing and then apply either fresh bore water or bore water with chemicals added to sanitise the water in the final rinse.

As part of a project initiated to manage bacterial breakdown in washed potatoes, a survey of washing sheds in South Australia was undertaken to determine the levels of bacteria in the processing line. Erwinia was found at varying levels throughout the washing line and the numbers of infected tubers increased when washed with water. While all sanitising agents tested killed Erwinia, Oxine and Klorman were effective when added to washing plant water containing bacteria, soil and plant material. Maintaining tubers free of surface moisture after bagging reduced the risk of bacterial breakdown in washed potatoes.

This project was funded by the Potato Industry levy with matched funding from the Australian Government facilitated through HAL.

More information

For more details contact: Barbara Hall

More info on research into managing bacterial breakdown (soft rot) in potatoes in series of Newsletters - Exposing Erwinia

Exposing Erwinia (PDF files)

A newsletter provided updates on the research into management of bacterial soft rot in potatoes.

Black dot

Black dot is a disease of potatoes that causes skin blemishes and possible yield loss. It is caused by the soilborne fungus Colletotrichum coccodes. 

Survives in the soil for up to 8 years. results in external skin blemishes, internal tissue discolouration of stem ends, yield reductions. Infected seed is the primary means of introducing the disease into new regions

HAL project PT01001, control of Black Dot in Potatoes - links to full html page report - project to develop management strategies to control the disease for both washed potato growers and seed growers

 

 

Potato early dying

Potato early dying (PED) is a serious disease of potatoes that causes plants to collapse and die prior to full maturity. It is associated with the combined infection of root lesion nematodes Pratylenchus.spp and the soil-borne fungus Verticillium dahliae.

Contact: Robin Harding, Barbara Hall.

Potato pink rot

Pink rot is caused mainly by the soil-borne fungus Phytophthora erythroseptica. It rots the tubers and kills plants, reducing yield and storage potential. It is generally associated with potatoes grown in poorly drained soils, has been found in well drained and managed soils, and in certified seed tubers. Management of disease development in storage is also important.

Potato pink rot control in field and storage  Pink rot of potatoes: screening fungicides using pot trials

Pink rot of potatoes screening fungicides using pot trials = the use of tubers potted in artificially inoculated soil was investigated as an alternative method of assessing the efficacy of fungicides to control pink rot. Results show that growing potatoes in soil artifically inoculated with Phytophthora erythroseptica is an effective method for screening fungicides for the control of pink rot.

Studies on Pink Rot investigations on cultivar susceptibility, the potential use of biofumigation and evaluations of fungicides for the control of Pink rot.

 

Rhizoctonia

Rhizoctonia solani is a fungus, common in potato crops, which results in reduced yields and poor quality tubers, including black scurf disease

Biological and Chemical Control of Rhizoctonia  a summary of the results of laboratory, shadehouse and field experiments carried out to evaluate potential biological agents and fungicides in the control of Rhizoctonia solani.

Understanding Rhizoctonia general information about the damage that Rhizoctonia can do, conditions for growth and prevention and management of Rhizoctonia canker and black scurf.

Control of Rhizoctonia on Potatoes report on experiments to assess the control of Rhizoctonia with a broad spectrum fungicide applied in furrow or to the soil surface, compared to seed treatments.

 

Seed and soil borne diseases

Disease management of potatoes on Kangaroo Island - technical summary of report which shows that KI has a low incidence of soil borne diseases compared to other seed potato growing areas of Australia.

Incidence of diseases on potato seed tubers - a study of the incidence of diseases that were present on potato seed tubers imported into the state show that changes in the potato certification schemes need to be undertaken to improve the health satus of potato seed tubers used in Australia.

Diseases in seed potatoes - discusses tuber borne fungal diseases, use of certified seed and certification schemes used throughout Australia, fungicide seed treatments

Incidence of diseases in potato tuber seed used in SA in 97/98 - none of the certified seed lots tested was disease free - the potato seed industry needs dramatic changes to improve the seed quality. Results suggest that soil in many seed production areas is infested with a wide range of potato pathogens.