Integrated disease management (IDM) for anthracnose, Phytophthora blight and whitefly transmitted geminiviruses in chilli pepper in Indonesia
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ACIAR Research Program Manager
The overall purpose of this project is to identify and demonstrate effective integrated strategies to limit losses to Phytophthora blight, Anthracnose, and Whitefly-transmitted geminiviruses in chilli peppers in Indonesia. The specific objectives of the project are to:
Assess and address the socioeconomic and horticultural practices affecting adoption of disease control options in Central Java;
Characterise biological factors affecting disease incidence and severity of anthracnose, Phytophthora blight, and whitefly transmitted viruses on chilli pepper;
Assess integrated crop management strategies for sustainable control of anthracnose, Phytophthora blight and whitefly transmitted viruses; and
Continue with the development of locally acceptable varieties carrying effective resistance to anthracnose and phytophthora blight, and search for lines resistant to whitefly transmitted viruses.
Project Background and Objectives
In Indonesia, chilli pepper (Capsicum spp.) is an important crop, providing income and nutritional benefits to smallholder producers. In 2003, over 550,000 t were produced, mostly in Java and Sumatra, with smaller production centres in Bali and Sulawesi. Productivity of chilli pepper is limited by disease pressures from fungi and viruses, which reduce yields and marketability, while increasing economic risks to the farmer. The two most serious fungal diseases are Phytophthora blight (PB), (caused by Phytophthora capsici), which causes wilting, defoliation, fruit drop, and plant death and anthracnose, (caused by Colletotrichum spp) which causes fruit lesions on immature green and mature red fruit thus reducing harvestable yield; fruit lesions may even develop several days after harvest, causing substantial post-harvest loss. On the other hand, Whitefly-transmitted geminiviruses (WTG) induce symptoms such as foliar chlorosis and curling, reduced leaf size, inhibited fruit set and abnormal fruit development. Chemical control measures are frequently ineffective or expensive, and farmers lack knowledge of innovative approaches to disease management. The development of satisfactory control measures is a high priority for AVRDC-the World Vegetable Center (AVRDC) and Indonesian R&D collaboration.
Progress Reports (Year 1, 2, 3 etc)
Project activities began in May, 2006. Indonesian partners in IVEGRI, AIAT, and IPB were confirmed. An organizing, Inception Workshop was organized and conducted in September, 2006, in Bandungan, Central Java, with all members attending except our Australian partners. Formal workplans and budgets were discussed and settled, as well as basic reporting responsibilities.
During October and November, pathologists and entomologists conducted surveys of the three targeted production regions, gathering plant and insect samples for isolation and evaluation of pathogen strains, primarily of phytophthora and WTG.
Inception Workshop, Bandungan, Central Java, September 4-8, 2006
Recruitment and hiring of our project Site coordinator, Dr. Anna Dibyantoro
Objective 1 (Assess socioeconomic and horticultural practices affecting adoption of disease control options in Central Java):
Planning begun for Rapid Rural Appraisal survey of three target areas. Initially scheduled for January, this activity was postponed to March 5-15, 2007, because of schedule conflicts and the transfer of AVRDC socio-economist Dr. Mubarik Ali to new duties in Pakistan).
A consultant, Mr. Joko Mariyono, was contracted to assist in the RRA activity. He will potentially be hired as a research specialist within AVRDC's socioeconomics unit, upon his completion of a PhD degree at Australia National University (Crawford School of Economics and Government) in Australia.
Objective 2 (Characterize biological factors affecting disease incidence and severity):
IVEGRI virologist and entomologist visited the target regions, and collected pepper plant sampled displaying symptoms of geminivirus: Magelang (3), Rembang (4), and Brebes (6). These will be studied further at IVEGRI laboratories. Live plants were also harvested and transferred to IVEGRI-Lembang for further studies. Whitefly samples were also collected, and rearing is underway at Lembang.
Designs were completed for construction of three screened inoculation rooms, to be used in 2007 for transmission studies of the geminiviruses, and for screening germplasm for virus resistance..
Collection surveys for Phytophthora and Colletotrichum pathogens were undertaken in January 2007, and will be reported on in next year's activity report.
Objective 3 (Assess IDM strategies for sustainable disease control):
Initial crop management trials were established in late 2006, in the Brebes area, on Surjan beds 1.5 meters wide x 25 meters long. Shallots were set in the blocks in December, and pepper seedlings were germinated in banana-leaf plugs under protective screen netting, to prevent insect and/or virus infection. These seedlings will be inter-planted among the shallot, and will be followed by disease protective treatments.
Objective 4 (Continue development of locally acceptable varieties carrying resistance to target diseases):
At AVRDC, segregating progenies were advanced and reselected during the fall season, and seed samples are being made available for follow-up testing in Indonesia. These include:
25 F3 progenies of a Kerriting variety crossed with potential sources of WTG resistance. 77 single plant selections were made based on horticultural type and yield potential, and will be shared with IVEGRI and IPB staff for screening with WTG isolates.
21 F4 progenies from crosses between the Phytophthora resistant line PI201238 and several Indonesian varieties (Jatilaba, Kerriting, and Tit Super) were screened a second time for resistance, and 29 single plants were selected for further refinement. Seed bulks of the resistant progenies were also harvested, and these will be sent to Indonesia for additional evaluation, screening, and reselection.
40 F5 and 21 F6 multi-disease resistant progenies based on a Jatilaba background (or Kerriting in some cases) were further reselected on the basis of resistance to anthracnose, yielding 25 F6 and 78 F7selections. Seed of these will also be shared with Indonesian collaborators for screening against local strains, and potentially used in farmer participatory selection trials.
150 accessions of Capsicum frutescens were established in a seed increase block to provide seed for screening in Indonesia for resistance to WTG
At IVEGRI, numerous Indonesian OP varieties are being increased in anticipation of screening them with locally isolated strains of phytophthora and anthracnose, which tasks are being accomplished by the mycologist. Screening of accessions for resistance to geminivirus awaits establishment of isolates, whitefly vectors, and inoculation chambers by the virology group.
This project seeks to reduce yield losses associated with selected disease of chili pepper in Indonesia: Anthracnose, Phytophthora blight, and Whitefly Transmitted Geminiviruses (WTG). Three important chili production regions in Central Java were selected (near Brebes, Magelang, and Rembang) for baseline surveys, evaluation of candidate innovations in production practices, and development of resistant varieties. In the past year we have: established a site coordinator's office in Tegal; conducted Rapid Rural Appraisals; established mycology research facilities at IVEGRI; conducted trials in farmers' fields, evaluating several candidate management innovations; and evaluated intermediate and advanced generation disease-resistant selections of peppers.
The Rapid Rural Appraisal (RRA) was implemented in two target villages in each of the three production regions, meeting with ten farmers who have intensively cultivated chili peppers for at least three years. The follow-up baseline study has been implemented to profile the socio-economic context of chili production, with particular focus on pest control strategies. Around 75 farmers (50 chili growers and 25 non-chili growers) are being surveyed in a village in each of three production regions; with 225 farmers in total. Household surveys, are currently being implemented and will be completed by July 2008.
Pathologists at IVEGRI, IPB, and AVRDC - The World Vegetable Center (the Center) have collected isolates of Geminivirus pathogens, which are being used in focused studies of virulence and symptom expression. Surveys of viral disease incidence in chili fields in 2007 found increased Geminivirus incidence almost everywhere, with scattered occurrence of other viruses. Isolates from chili plants from at least five sites in the Magelang area have been comfirmed as WTG via PCR analysis. Characterization of geminivirus isolates based on restriction enzyme patterns has identified at least 6 distinct patterns. Common patterns were found in accessions from Brebes, Magelang, and Yogyakarta areas; unique patterns have been found in collections from the Rembang area, and patterns found in Magelang in 2006 differed from those collected and identified in 2007, indicating a highly fluid situation.
Incidence of the fungal diseases phytophthora and anthracnose has been documented in 20 locations surveyed in Java during 2007-8. Anthracnose was encountered in all sites, while light to moderate incidence of phytophthora was found in only 8 locations. Seventy collected isolates of Colletotricum have been characterized for species and relative virulence. Fifty two isolates were found to be Colletotricum acutatum, ten are C. capsici, six are C. gloeosporioides, and two are C. boniense. C. capsici accessions appear to be the most virulent.
Crop management trials conducted during 2007-8 included evaluation of a combination of plastic mulch, bio-fungicide, or synthetic fungicide. Silver-plastic mulch delayed (but did not prevent) the spread of virus infection, reduced losses due to fruit fly, soft rot, and anthracnose, and produced higher total and marketable yields, compared to non-mulched treatments. The synthetic fungicide (Bion-M) significantly reduced (but did not eliminate) losses due to anthracnose. A second trial compared bio-fungicides to synthetic fungicide on beds with or without rice straw mulch. Mulch delayed and reduced incidence of virus symptoms. Inclusion of bio-fungicides in spray programs significantly reduced anthracnose losses.
Physical barriers to reduce whitefly movement, and consequent virus infection were studied in a farmer's field near Magelang. Plots established with or without Nylon netting either one or 1.5 meters in height, and sub plots were treated with or without insecticidal sprays. Preliminary data suggest that the taller barrier is effective in reducing whitefly entry and disease incidence. Total yields of plots with the high barrier and insecticidal sprays were more than double that of untreated plots that simulated conventional farmer practice. Unfortunately, losses to anthracnose in this trial exceed 50% of the harvested crop, regardless of treatment. We are already seeing local growers imitating this treatment by erecting barrier walls of various sorts around their chili gardens.
Breeding efforts have commenced with seed increase of candidate sources of resistance to Anthracnose or Phytophthora, and numerous intermediate and advanced generation selections carrying disease resistance provided by the Center. Forty four chili lines were screened for resistance against examples of the four Colletotrichum species, and promising entries were identified, especially AVRDC line 0636-6515, which displays resistance to three species. Fourteen chili genotypes were evaluated for geminivirus resistance in an open field planting near Yogyakarta; while all lines developed at least 20% disease incidence after 60 days, a few (especially IPB C46) displayed significantly less incidence than most of the lines tested.
In summary, the project activities are being implemented in farmers' fields and on-station trials in Indonesia, as well as in the Center in Taiwan; and they are on schedule as proposed earlier.
Project activities during 2008-9 have affirmed the severity of Anthracnose and whitefly-transmitted geminivirus, but losses due to Phytophthora wilt have been less than expected. Research trials have progressively moved from research stations to farmer fields, contacting as many as 200 farmers with participatory trials, field demonstrations, and Farmer Field Meetings. A baseline survey characterising chilli cultivation practices with special regard to pests and diseases at individual farm household level has been completed in the targeted regions (Brebes, Magelang, and Rembang); the summary report is being finalised.
Pathogen isolates collected in 2006-7 have been characterized; Anthracnose is caused predominantly by Colletotrichum acutatum while Phytophthora strains are mostly the severe pathotype 3. Several lines of chilli were identified as resistant to Java isolates of Phytophthora, including several of the 'cabe rawit' type (Capsicum frutescens), an important chilli crop in Java which has received relatively little attention. Some 92 lines were screened for resistance to whitefly-transmitted geminivirus in chambers at IVEGRI, and15 were found to be immune to infection. Single plant selections are being increased, and will be retested to confirm their resistance. The improved inbred variety 'Tit Super', typical of the varieties grown in the Brebes region, proved to be moderately resistant, which may explain why virus incidence here is less than in other areas.
Seven AVRDC-contributed advanced lines were identified as promising, but farmer reaction has been cool, as yield potential and fruit type do not match commercial needs, despite reduced losses to disease. The commercial hybrid variety 'New Taro' was favoured by the farmers because of high yield potential, favoured fruit type, and some modest resistance to anthracnose.
Tests of cultural practices for disease reduction included paired comparisons of current farmer practice to a package of recommendations (protected seedling production, rice-straw mulching, regular application of a bio-pesticide formulation [Bacillus subtillis], and periodic soil drench of a 'compost tea' [effective microorganism suspension]). Four replications of this comparison were established with cooperative farmers in the Brebes area, and was the focus of a farmer field day in April, 2009, attended by more than 50 local farmers. The fields clearly displayed evidence of increased vigour (taller, denser plant canopies), improved fruit set, and reduced incidence of wilted plants in the plots using the recommended practices.
In the Magelang area, farmer cooperative trials in five sites are testing the effectiveness of three barrier strategies (1.5 meter tall nylon netting, maize, and yard-long bean). This trial is combined with Farmer Field Meetings on a monthly basis, at one or more of the trial sites, where background information on this trial, as well as other topics, is shared with the farmers. Previous year's trials of the barrier technology met with clear farmer interest, which continued into this trial. These barrier technologies have a good chance of spreading to the other districts through national agricultural extension system cooperating with the trials.
Trials in Rembang focused on drip irrigation/plastic mulch combined with border plantings, in an area where water is scarce during the dry season. Trial results showed some yield improvement, and a delay in the spread of geminivirus infection by 2-3 weeks (drip irrigation delayed virus incidence even without barrier netting). Farmers have been positively impressed with the labour savings aspect of the drip system. The costs of labour to irrigate and control weeds were cut in half, making the crop significantly more profitable.
At AVRDC, support research included the following:
Evaluation of yield and disease incidence in several Indonesian pepper varieties (and one AVRDC line) under drip vs. furrow irrigation. Drip irrigation consistently increased yields, reduced incidences of powdery mildew and root rot (due to Pythium sp.), and substantially improved water use efficiency, compared to furrow irrigation.
Evaluation of net barriers in combination with an insect growth regulator (pyriproxyfen) in controlling infestation of whitefly. Nylon netting of 50-mesh was effective at excluding whiteflies (but not aphids, mites and thrips) while 32 mesh was not effective. Where applied, the insect growth regulator effectively reduced whitefly count
Screening of additional germplasm for resistance to the target diseases. A total of 758 accessions representing 6 species were screened for resistance to Phytophthora, but no new sources were identified; 11 out of 129 accessions from the AVRDC pepper breeding program were identified as resistant to severe strains of Phytophthora. Seed shipments of more than 150 lines of intermediate and advanced generation selections carrying resistance to one or more diseases were distributed to project partners. Many of these lines have the preferred long thin 'keriting' (curly) type chilli in their parentage.
Continuing surveys of disease incidence, in Java and nearby islands, have confirmed that severe begomovirus infection persists in the Magelang and Yogyakarta Regions, and equally devastating Anthracnose incidence is encountered in all areas during the rainy season. AVRDC staff provided further training and coaching in the utilization of molecular methods of species identification within Colletotrichum spp., and within Phytophthora capsici. More than two hundred Colletotrichum isolates have been collected by IVEGRI and IPB, mostly identified as C. acutatum and C. capsici. Using standard differential host inoculations, the severe pathotype 3 of P. capsici was found to predominate in most fields, although of the less virulent pathotype 2, or mildest pathotype 1, predominate in some locations (Brebes and Lembang-site2, respectively). Diversity among begomovirus isolates attacking pepper indicates at least two distinct species: Pepper yellow leaf curl Indonesia virus (PepYLCIV), and a new, unnamed diverse cluster of entries. In Taiwan, the first instance of a begomovirus (Tomato yellow leaf curl Thailand virus - TYLCTHV) infecting pepper was reported.
Using morphological keys, and Cytochrome oxidase I (COI) sequencing, three whitefly species were found in or near pepper fields. Only Bemisia tabaci is implicated as a vector of begomoviruses, and is limited to warm elevations (< 1200 meters). B. tabaci populations in a chili field were quantified weekly for 4 months. Adults and (later) nymphs were found in the chili pepper field soon after transplanting, and increased steadily until 8 weeks after transplanting. Populations subsequently declined, possibly related to an increased detection of nymphs parasitized by Eretmocerus spp. Many weed species found in association with pepper fields had substantially higher populations of B tabaci than the peppers, and at least 10 species have proved to be potential alternate hosts to the begomovirus strains that attack peppers.
Integrated Crop Management (ICM) trials in Brebes emphasized the efficacy of straw mulch, bio-pesticide (largely Bacillus subtilis), and 'compost tea' for protection from disease development. Treated plots showed not only reduced losses due to wilting (Phytophthora and/or bacterial wilt) but improved flowering, fruit-set, and yield.
In Magelang, and also Rembang, use of crop barriers to reduce begomovirus infection were presented to farmers in multi-location trials and farmer meetings. Some farmers have been stimulated to reuse old plastic mulch sheeting and other discarded panels to simulate the method. Research trials have moved on to living barriers - yard-long beans, maize and the green manure legume Crotalaria juncea. Farmers are very receptive to the Crotalaria barriers, as it occupies less space than equivalently dense maize planting. It reportedly delays virus symptom onset by several weeks, resulting in higher continuing yield.
Other ICM trials are introducing drip irrigation to farmers in seasonally dry areas near Rembang. Drip irrigation in conjunction with nylon net barriers reduced begomovirus damage. The technology also appeals to farmers because of the potential savings in labour cost for irrigation and improved water use efficiency. Ongoing trials at AVRDC have shown that drip irrigation can sustain high yields with less water compared to furrow irrigation, and can reduce plant losses to wilting.
Evaluation of AVRDC candidate selections has been somewhat disappointing. Although some lines are reported to be resistant to anthracnose in lab tests, resistance has not been stable in field trials, and fruit type does not match local preferences. A few lines currently being evaluated in Rembang, such as 0537-7558, are potentially resistant to both whitefly transmitted geminivirus and anthracnose, and displays commercially acceptable 'cabe besar' fruit type. Additional multi-disease resistance lines with attractive agronomic and horticultural features continue to be generated at AVRDC for testing in Java. High resistance to P. capsici has been found in several introduced genotypes of Capsicum frutescens ('cabe rawit') (C04851, C04870, C04871, C04872, and C04843).
Extensive surveys of chili farming communities has resulted in the published 'Baseline Report: Chili production practices in Central Java, Indonesia (2009)', which characterizes the economic and social context of chili pepper farmers, emphasizing the crop's higher risk profile, as well as its special opportunities. AVRDC's popular, illustrated, "Pepper Diseases: A Field Guide" has been translated into Bahasa Indonesia, with a printing of 2000 copies; reception among chili farmers has been very favourable.
These technologies have been presented to more than 200 farmers in farmer field meetings and demonstrations. The project was granted a six-month no-cost extension, until October 2010, in order to effectively utilize available funding, and to advance farmer awareness of the benefits of the candidate disease management technologies, to further evaluate promising advanced lines of disease resistant peppers, and to conduct impact assessments.
There are no project locations defined for this project.