Diseases of crops in the central provinces of Vietnam: diagnosis, extension and control

Objective 1: Training of provincial staff in basic laboratory diagnostics
Three training workshops have now been held. The first, at Hanoi Agricultural University (HAU), in November 2005 involved basic training in laboratory techniques, in Vietnamese, by project staff from HAU

Subsequently two workshops were held in Quang Nam, in January and April 2006 for six staff from all three provincial laboratories. Each of these workshops involved disease surveys of key crops, diagnostic training in the laboratory and farmer consultation focussing on ginger, peanuts and the major vegetable crops. The surveys also contributed to Objective 3. These two workshops also integrated with the formal training in diagnostics and field work. English support was provided by Mrs Jillian Burgess and proved very successful. We can now communicate reasonably well by email directly with three of the six young laboratory staff. Equally importantly they can now make some use of the written resources provided in English. Australian team members can now interact directly with two of the three provincial centres (Quang Nam and Hue).

Objective 2: Establish basic fungal diagnostic laboratories
The diagnostic laboratories were established and operational by January 2006, in time for the first surveys.

Objective 3: Implement limited surveys of nominated fungal diseases
Intensive surveys of quick wilt of black pepper and pathogenicity tests have shown that this diseases is caused by Phytophthora capsici. This work is part of Mr Nguyen Vinh Troung's PhD. Intensive surveys of pineapple heart rot and pathogenicity tests have shown that Phytophthora nicotianae is the dominant Phytophthora species involved. This work is part of Mrs Dang Luu Hoa's MScAgr degree. The cause of ginger decline surveyed in January has not been determined. It will be a focus of studies in January 2007 and Dr Mark Fegan (University of Queensland) is assisting with the identification of bacterial cultures from diseased plants. Preliminary studies on peanut root rot suggest it is caused by a complex of fungal pathogens including Pythium sp. An intensive survey of this disease will be undertaken in April 2007. Didymella sp. was the only pathogen associated with the limited outbreaks of watermelon gummosis surveyed in April.

The surveys of fungal diseases of vegetable crops in Quang Nam, a part of the training workshops in January and April revealed that Sclerotinia sclerotiorum is a key disease of short and tall beans and that Phytophthora capsici, Sclerotium rolfsii and Ralstonia solanacearum are key pathogens of chilli (a major crop). Furthermore bacterial wilt, caused by R. solanacearum, was diagnosed in a range of other crops such as tomato, bitter melon and tobacco based on isolations from farmer supplied samples and survey samples. This pathogen is obviously of significant economic importance. The disease in the past may have been mistaken for Fusarium wilt.

The initial survey of coffee decline indicates that the problem may be a consequence of termite damage of the bark of the upper tap root and lower stem, which facilitates infection by fungal pathogens which then develop a slowly spreading root rot.

Objective 4: Establishment of farmer reference groups and participatory training/liaison activities
See comments under Objective 1.

Objective 5: Pathogenicity tests of cultures from surveys
Pathogenicity tests have been completed to demonstrate that Phytophthora nicotianae is the major cause of pineapple heart rot and P. capsici is the major cause of quick wilt of black pepper. Pathogenicity tests have also been completed with R. solanacearum, S. rolfsii and S. sclerotiorum.

Objective 6: Implement field trials to evaluated control measures
A small field trial was initiated in late 2005 to evaluate methodology for treating black pepper with phosphonate, following successful screenhouse trials. The results of fungicide trials in the screenhouse for control of pineapple heart rot are being analysed, but several treatments were clearly successful. Major field trials in control of both diseases will be initiated in the summer of 2007. The feasibility of trialling insecticides to control termite damage in coffee seedlings and young trees is being discussed with entomologists in the Northern Territory and Vietnam

Objective 7: Production and distribution of model teaching materials. Dissemination of findings formally and in-country
No major modifications proposed to this objective. However the manual on basic diagnostic guidelines for fungal plant diseases commissioned by ACIAR will provide an invaluable resource for teaching and day-to-day activities of staff in provincial and other diagnostic laboratories in Vietnam. Professor Burgess and Mr Timothy Knight have brought together a wide range of illustrative material for use in this manual. This will be useful in preparing other training materials.

Objective 1: Training of provincial staff in basic laboratory diagnostics

Two workshops were held in Quang Nam, in January and April 2006 for seven staff from all three provincial PPSD's and Hue UAF. Each of these workshops involved disease surveys of key crops, diagnostic training in the laboratory and farmer consultation, focussing on ginger, peanuts and the major vegetable crops. The surveys also contributed to Objective 3. These two workshops also integrated English training with the formal training in diagnostics and field work. English support was provided by Mrs Jillian Burgess and proved very successful. We can now communicate reasonably well by email directly with five of the seven young laboratory staff. Equally importantly they can now make some use of the written resources provided in English. Australian team members can now interact directly with two of the three provincial centres (Quang Nam and Hue).

Five district staff from Quang Nam were included in the April Workshop. Their involvement was invaluable as they will be involved in the long-term delivery of advice on plant disease directly to farmers. They were enthusiastic and proved quick to learn laboratory skills. All were recent graduates. One of the district staff has now joined the Quang Nam project team! The third intensive workshop was initiated on December 26 and was completed on 27 January 2007. Again English training was integrated into the diagnostic and research training.

Objective 2: Establish basic fungal diagnostic laboratories
Completed as originally planned. Savings on travel expenditure were allocated to the provision of some basic equipment to establish a small laboratory at Hue PPSD where two staff have been trained in our program. This decision followed a request from these staff and their Director and was made in consultation with the Project Leader, Vietnam.

Objective 3: Implement limited surveys of nominated fungal diseases
See previous report for details of surveys and findings on quick wilt of black pepper and pineapple heart rot. An intensive survey of ginger wilt in Quang nam was initiated in December 2006, involving all team members from the three provinces. Invaluable discussions were held with farmers who advised that they recognised two types of symptoms, "one where the plants appeared to have boiled in water" and collapsed within a few days, and the other one where plants yellowed and wilted very slowly. Subsequently the bacterial wilt pathogen R. solanacearum was detected using a Pocket R diagnostic test kit and suspected cultures of the pathogen were isolated. This pathogen is thought to cause the 'boiled water' symptom. The yellowing (slow wilt) was linked to Fusarium oxysporum known to be a pathogen of ginger in other countries. Root knot nematode was also discovered on ginger and was most common where F. oxysporum was isolated commonly. This nematode has been shown to increase the incidence of Fusarium in wilt in some crops in other countries. A preliminary survey of gummosis in watermelon indicated that DIdymella sp. is the pathogen responsible for this disease in Hue. Dry conditions in Quang Nam iprevented disease development.
An intensive survey of potential root-rot fungal pathogens of peanuts seedlings was initiated in December in Quang Nam involving the whole team. The initial results indicated Pytium species were the dominant pathogen species, together with Rhizoctonia sp. and Aspergillus niger. The seedling survey and a survey at mid-pod stage will be conducted in each province in March and April/May respectively.. Phoma terrestris (pink root rot pathogen) was identified causing losses in Vietnamese onions in Quang Nam province following requests for advice from farmers. This is the first report of this disease.
Further study on coffee decline indicates that the problem may be a consequence of termite damage of the bark of the upper tap root and lower stem, which facilitates infection by fungal pathogens which then develop a slowly spreading root rot.
Pythium species and Phytophthora species were found in nursery transplants of several vegetable seedlings. This raises issues for disease management which are discussed under Objective 6.

Objective 4: Establishment of farmer reference groups and participatory training/liaison activities
Invaluable discussions have been held in the field with farmers on each of the major diseases being considered. The Quang Nam PPSD has been working with 50 vegetable farmers to promote the adoption of fungicide application for the control of Scleroteria stem rot in beans, together with rotation.
Discussions were held in December with ginger growers about the problem of contaminated rhizomes used for planting. Plans for field trials were also discussed to asses the feasibility of different heart rot and quick wilt of black pepper.

Objective 5: Pathogenicity tests of cultures from surveys
Pathogenicity tests of the putative pathogens from ginger are planned for 2007. However a supply of pathogen-free ginger has not yet been identified. Note that pathogenicity for Phytophthora capsici to black pepper , and
P. nicotianae for pineapple heart rot were completed across 2005-2006. Didymella sp. was shown to cause gummosis in watermelon in a preliminary test. The provision of a supply of pathogen-free coffee seedlings is an issue and is discussed under (6).

Objective 6: Implement field trials to evaluate control measures
Field trials on control will be implemented in 2007 for pineapple heart rot, quick wilt of black pepper and the wilt complex in ginger. As diseases of vegetables and field crops are identified during diagnostic training, advice is extended to farmers, if the control measures are well established in other countries.

Following discussions with Dr Ngo Vinh Vien, Director of NIPP, crop rotation and the development of pathogen-free transplants, rhizomes etc will be highlighted in training and extension activities.

Objective 7: Production and distribution of model teaching materials. Dissemination of findings formally and in-country
No Modifications to this objective. Discussions have already been held with the project team to initiate ideas on extension materials.