ACHIEVEMENTS, CHALLENGES & SOLUTIONS IN BLACK PEPPER (Piper nigrum L. ) PRODUCTION IN

Bui Chi Buu, Institute of Agricultural Sciences for Southern Vietnam, 2014 [email protected]

With a quick increase of growing areas and the intensive cultivation of black pepper over the past ten years, disease problems would naturally set in and widely disseminate. Depending on the management practices in each region, the disease severity would vary considerably from time to time. Most of the disease problems are quite similar in some black pepper growing areas of the country. This is due to the inherent susceptibility of the cultivars commonly grown in the region to pathogens, and also due to the propagation of infected planting materials, the later often being the case in the spatial spread of the disease within the region. In Vietnam, there are six major pepper production areas as Gia Lai, Binh Phuoc, Dong Nai, Dak Nong, Dak Lak, and Ba Ria with the total production of 105-110 thousand T, annually and cultivated areas of 52,000 Ha roughly (Table 1).

Table 1: Black pepper production (tonne / year) in Vietnam with cultivated areas of 52,000 ha.

Year 2011 2012 Country 105,035 110,000 Target areas Gia Lai 27,773 28,200 Binh Phuoc 26,155 24,565 Dong Nai 13,111 13,318 Dak Nong 13,096 13,238 Dak Lak 11,715 14,049 Ba Ria 11,725 11,630 Others 5,000 5,000 Productivity (t / ha) 2.14 2.20

Black pepper obtained high productivity (2.0-2.4 t/ha). The contribution of soil fertility, healthy variety, organic approach, and well drainage accounted for 35.35, 30.30, 25.25, and 10.10% (Bui Chi Buu 2012).

Table 2: Added-value promoting via pepper processing

Production (MT) 2011 2012 Total product (MT) 104,842 110,000 (%) BLACK 85.2 86.0 (%) GRINDED BLACK 7.4 8.2 (%) WHITE 14.8 14.0 (%) GRINDED WHITE 2.4 3.0

Added-value promoting via pepper processing has been still a shortcoming in Vietnam. Grinded black and white pepper products accounted for 7.4 and 2.4%, respectively in 2011 and 8.0 and 3.0% in 2012 (Table 2). Other processed products with highly economic value as medecine oil are still very rare. Vietnam has become a first pepper exporter in Europe, Asia, America and Africa with its shared markets of 39.2, 36.6, 15.3 and 9.0%, respectively. Vietnamese pepper now was exported to roughly 80 countries in the world. Top ten markets importing black pepper from Vietnam could be listed as: the USA, Germany, United Arab, the Netherlands, India, Egypt, Singapore, Spain, the UK, and Russia.

FULLY RISKY PRODUCTION?

In Vietnam, the incidence of diseases and pests on black pepper was recorded in the early half of 20th century (Chevalier, 1925; Biard and Roule, 1942). Pepper growing area in Kien Giang and Ba Ria-Vung Tau provinces declined from 930 thousand stakes in 1910 to 540 thousand stakes in 1927 due to diseases, in which foot rot was the most destructive disease (Barat, 1952). Phytophthora foot rot has been considered as the most devastating disease of black pepper in Vietnam. The highest level during May to November was recognized annually. Survey and research reports in the past 25 years showed that diseases and pests incidence, especially foot rot disease, is the main problem confronting the sustainable development of black pepper in Vietnam (Nguyen Phi Long, 1987; Pham van Bien, 1989; Nguyen Ngoc Chau, 1995; Nguyen Thi Chat, 2001; Nguyen Tang Ton, 2005; Ngo Vinh Vien, 2007; Plant Protection Department, 2007; Nguyen Tang Ton, 2011). Serious soil-borne diseases and diseases enhancing insect are demonstrated in Table 1. Overuse and misuse of chemical fertilizers and pesticides caused the unsustainable development. We have looked for the suitable solution so far.

Table 3. Major diseases and pests on black pepper in Vietnam No. Diseases and pests Causal agents Infected parts Level 1 Foot rot Phytophthora capsici Collar region, roots +++ 2 Slow decline M. incognita, R. similis Roots +++ 3 Stunted PYMV, CMV, TMV, Badna virus Leaves, shoots + 4 Root rot Rhizoctonia sp., Fusarium sp. Collar ++ 5 Leaf spot Diplodia sp. Leaves + 6 Leaf blight C. gloeosporioides Leaves ++ 7 Algae leaf spot Cephaleuros virescens Leaves, branches, fruits ++ 8 Mealy bug Pseudococcus sp. Leaves, branches, fruit ++ spikes, stem, collar Note: (+++) very popular; (++) popular; (+) rare Source: Nguyen Tang Ton, 2005

Phytophthora foot rot, considered the most devastating disease of black pepper, has been reported to cause an annual crop loss of 5-10% (Kueh, 1990) and up to 95% for individual farmers (Manohara et al. 2004). In Vietnam, the disease occurs with the highest level during the rainy season (May to November). Early infection shows the lesions with minute spots on leaves near the ground, becoming specific fimbriate edge leaf lesions. The disease is usually undetected by farmers and technicians until the upper part of pepper vine shows symptoms of leaf yellowing, wilting and dropping (Nguyen Tang Ton, 2005). Once these symptoms are observed, the infection is already at its severe stage with most of the root rotted and the underground stem showing a brownish-black lesion. At this stage, the infected collar is invaded by secondary micro-organisms. Rotting of collar and roots induces a discontinuation of water and nutrition transport between the underground parts and the upper parts of the plant; this causes symptoms of sudden leaf wilting and dropping. In many cases, leaves turn black but still hang on the dying vines for weeks or months. The disease progresses rapidly, especially during the rainy season and the plant death occurs within 2-3 weeks. In Indonesia, Manohara and Rizal (2002) reported that the surrounding plants adjacent to an infected plant become infected after one or two months, this dissemination is more quickly during the rainy season. Main reasons and causal agents inducing and spread foot rot disease are described in Table 3.

Table 3. Main causes of foot rot of black pepper in major pepper growing areas of Vietnam

Evaluation† Causes (%) Runoff water from infected gardens 96.1 Soils of high humidity 68.6 Phytophthora capsisi Nematodes 31.3 Unbalance fertilization 27.4 Clean weeding 13.7 Susceptible cultivars 11.7 Mealy bug 5.8 Excessive irrigation 9.8 Inherent fungi 5.8 Bumping crop 3.9 Heavy rain 1.9 Deep planting, no ridging 1.9 Note: † compared with normal case Source: Nguyen Tang Ton, 2005 Beside that, parasitic nematodes as Meloidogyne incognita, Radopholus similis are newly occurred. They became attracted a special attention by agronomists and pathologists. The slow decline is also paid more attention to have appropriate solutions. With the symptom of slow growth, leaves turn to yellowish green, then pale yellow leaves gradually drop from the lower to the upper parts of the plant, it could be said that a complex exhibiting by mixed symptoms of Fusarium solani, Colletotrichum gleosporioides,Rhizoctonia solani, Cephaleuros mycoides and Rosellinia sp.

SUGGESTED SOLUTIONS

The Prime Minister launched the Order 124 in Feb. 2, 2012 that we have to stabilize 50,000 ha of black pepper according to the planning of 2020 and the vision of 2030. It really needs a holistic approach with the empasis on (i) cultivars resistant to foot rot and slow decline; (ii) integrated crop management strategies (ICM); (iii) examining and defining effective practices of each component. Pepper is grown either alone or in mixed gardens, e.g. with robusta coffee on farms in Chau Duc district (Ba Ria-Vung Tau). This is one form of diversification which may help to minimize financial risk when prices vary, and biological risk due to pests and diseases in the environment. The advantage of pepper-coffee intercropping is that farmers supply enough water to coffee and a little amount of water to pepper, there is no water logging in the root zone of pepper plants, and proportion of Phytophthora infected plants and slow decline index of pepper plot decreases significantly. In addition, some forms of ley farming will be necessary to help regenerate soil fertility and to break pests and diseases cycles in monocultural pepper production systems. Without rotation, pepper plants of second generation grown on the same field could not develop normally and give berry, plants die off after 3-4 years of planting (Nguyen Tang Ton et al. 2011). Principal component analysis shows the effectiveness of each method in ICM as compared with that in farmers’ practice (Table 4). Table 4. Prevention and control measures for foot rot and slow decline Effectiveness† Prevention and control measures (%) Good drainage systems 94.1 Plant health maintenance 58.8 Organic fertilizer application 49.8 Balanced inorganic fertilizer application 48.3 Agro-chemicals and bio-fungicide application 47.6 Cover crops, mulching 39.8 Liming 33.3 Foliar fertilizer application 1.9 Limited upturning soil 1.9 Ridging, shallow planting 1.9 Note: † compared with farmers’ practice Source: Nguyen Tang Ton, 2011

Foot rot or quick wilt caused mainly by Phytophthora capsici and slow decline caused by nematodes, mealy bug and other soil-borne fungi fungi are main factors causing the degradation of pepper gardens. In many pepper orchards, these two diseases brought about slow growth and death of pepper vines, in some cases 100% pepper vines died off. Varietal resistance does not successfully affect. Good drainage in the rainy season, water- saving irrigation including drip irrigation and under-shade sprinkler minimise the spread and contamination of diseases, and significantly reduce the incidence and yield loss of pepper gardens. Mulching and planting of cover crops, such as Arachid pintoi and Stylosanthes sp., do not reduce the population of destructive micro-organims but these measures help to improve soil nutrients and regulate soil humidity, hence improve plant health. The integrated crop management of black pepper is considered the best practice in limiting the outbreak of soil-born diseases of black pepper, this procedure help to keep a stable yield of black pepper gardens and contribute to a sustainable development of black pepper. Field satinary withouth decayed plants and weed control to facilitate the well drainage was recommended. Timely application of manure and micro-nutrients with micro-organism products, namely Trichoderma harzianum, Pseudomonas fluorescens and Bacillus sp. help to limit the development of foot rot and slow decline in black pepper with 40 gr / hill two times (early rainy season and mid one) in addition of 10 ton of organic fertilizer / ha. In May to June (early rainy season), treatment of Metalaxyl 500WP or Mancozeb 80WP (5l / hill) was conducted and replication was doen in mid rainy season (August or September). Do not oversuse insecticide and fungicides. VARIETAL IMPROVEMENT

Actually, more attentions are paid to seed technology rather than high yielding variety improvement, because it will take long time with many challenges to perfect the breeding objectives. In Vietnam, we have a diverse collection of breeding materials as o Small-leaf genotypes including Tieu Se, Tieu Son, Se Dat Do, Phu Quoc, Nam Vang. o Medium-leaf genetypes: Lada Belangtoeng, Karimunda, Penniyur, Kuching. o Large-leaf genotypes: Tieu Trau, Se Mo, Trau Dat Do Free virus seedlings now are mentioning in some pepper farms with micropropagation + phytohormone treatment (1,000 ppm NAA at 30-60 days after growing in seedbed). There is no pepper variety resistant to foot rot and slow decline. In Vietnam, Lada Belantoeng variety imported from Madagascar in 1947, widely grown during 1960s and 1970s, showed rather high tolerant to foot rot (Phan Huu Trinh et al., 1988). The problem is that this variety was degraded after a longtime of vegetative propagation, resulting in less fruit setting, low yield and small seed. Indian cultivars (Karimunda and Panniyur 1) imported from India during the early 1990 show promising in the first 3-4 years after planting, less suppressed by foot rot and slow decline, but due to well vegetative growth, their yield and seed quality decline gradually (Ton Nu Tuan Nam, 2005). Vinh Linh and Tieu Trung varieties, their origin is unknown, perform well in many pepper growing regions with low incidence and yield loss from diseases. Other advantages of these two varieties are early fruit setting and high peppercorn quality. However, sometimes and somewhere there have been outbreaks of diseases, especially foot rot (Nguyen Tang Ton, 2005). In production, black pepper is commercially propagated through cuttings; the propagation through seed is carried out mainly in breeding and screening programs. With vegetative propagation, it is enormous that all cuttings are disease-free and are taken from disease-free gardens. In Vietnam, farmers commonly use their own cuttings or cuttings from neighbors as planting material, this is a problem in the dissemination of latent infected planting material from fields to fields. Agricultural authorities and extension agencies at different levels have encouraged farmers to purchase planting material from registered nurseries. Grafting work using Phytophthora capsici resistant P. colubrinum as rootstocks and P. nigrum as scions was tested. After five years of planting, no abscission of the scion were recorded, but the grafted pepper showed the symptoms of drought stress during the dry season and had fewer fruit spikes, hence gave lower seed yield (Nguyen Tang Ton, 2010).

WATER SAVING

Under canopy irrigation, drip irrigation have been recommended and implemented in large scale areas so far with the average investmant of $US 1,000 / ha. Today 35% of black pepper farms apply the technology. In Phu Quoc, furrow irrigation is a popular practice and the interval between irrigation is 8-10 days. In other pepper producing areas, confined irrigation is practised with an interval of 5- 7days. In Ba Ria-Vung Tau, some farmers practise micro-sprinkler, this is a good practice helping to save irrigation water in the dry season, especially in time when underground water is depleted. In Phu Quoc, irrigation furrows are also used as drainage systems in the rainy season, therefore all pepper orchards have the drainage systems, whereas in Quang Tri, Southeastern region and Central Highlands this figure is only 45%.

MANURE TREATMENT

Manure was treated by Trichoderma against Phytophthora foot rot lower 22% of infected plants and 78% of Vietnamese farmers adopted this practice and the incidence of diseases decreased 22.8% (Nguyen et al. 2005). Organic farming approach is beeing recommended and will be promoted soon.

CHALLENGES • Need 600 labor days / ha with high cost (DOCP-MARD 2012) • Investment / ha: – 8-9 times as compared to rubber – 3.5-4.5 coffee – 4-5 fruit orchard • Poor selection of seedlings causing disease transmitting in large scale • Loss # $ 5 million / year due to poor efficiency of N application

From scientific informations to farmer knowledges is a long road. How to make a correct decision in farmer fields, to gain more income through added-value and to assure food safety are the challenges to meet the demand of farmer livelihood. Good drainage in the rainy season, water-saving irrigation including drip irrigation and under-shade sprinkler minimise the spread and contamination of diseases, and significantly reduce the incidence and yield loss of pepper gardens. However, there are no evidence about the effectiveness of the drainage on the population of nematodes in soils and pepper roots.

LESSONS 1. Looking into the future is risky due to black pepper extending areas without planning 2. Breeding and IPM is still considered as the heart of the production with the emphasis on seed technology and organic approach 3. How to shorten the process from scientist information to become farmer knowledge not to overuse chemical applications, especially spice crops.

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