Spread of Phytophthora capsici in Black Pepper (Piper nigrum) in Vietnam

Van Long Nguyen 
Research and Development Pepper Centre, The Western Highland Agricuture and Forestry Science Institute, 
Pleiku City, Vietnam

1. Introduction

       Black pepper is one of the most important export products in Vietnam, contributing to socioeconomic development. It recently is quickly expanded in both area and yield. According to report of Vietnam Pepper Association— VPA, 2014. The estimation of pepper growing area is about 73,500 ha, in which 53,000 ha are productive. The average pepper yield is about 2.5 tons∙ha.

       Pepper products were exported 156,396 tons, accounting for 58% total worldwide export, brought $1.2 billion to Vietnam in 2013. Pepper area increases an average 2800 ha∙year between 2011 and 2014, and it will continue rising in the future. 

      In order to get great achievements, pepper producers had applied advanced technologies and cultivations on farms. For instance, increase in organic materials, decrease in chemical fertilizers, use of live supports and drainage systems are applied. However, Vietnam’s pepper production is facing extreme problem, relatived to threat of diseases. Statistics of VPA indicated from 2012 to 2014, pepper area was decreased about 2% year (1200 ha) resulted from aging and diseases. In Gia Lai province specifically, pepper yield was dropped up to 30% in 2014 compared with 2013. The main and most serious disease on Vietnam’s pepper areas is foot rot/quick death/phytophthora rot, which is caused by Phytophthora capsici.   
       Phytophthora capsici (P. capsici) is one of the most important vegetable pathogens worldwide, which was in-troduced by. It is an oomycete soil-borne plant pathogen that causes root, fruit and foliar disease on a variety vegetables. Plants that are infected by this pathogen will die within 2  - 3 weeks in rain and adjacent plants will be infected within one or two months. Quick death of Piper nigrum can be presented that phytophthora spores develop into the roots and stems, especially collar causing foot rot (Figure 1). Rotting of collar destroys phloem and xylem, preventing transfer of water and nutrient from the roots to aerial parts of plant. Therefore, plant died intermediately with symptoms of sudden leaf wilting and dropping. Importantly, the first symptoms of disease are very hard and often undetected by farmers and technicians. They detected disease when the upper part of pepper vine shows a performance as leaf yellowing, wilting and dropping. Once these symp-toms 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.   
P. capsici causes significant decline in pepper yields in all pepper producing countries and it is very hard to control. For example, foot rot in Indonesia resulted in degradation of pepper production from 5% - 0%, yield decline is up to 30% - 40% in some gardens and others can devastate 100% [15. Malaysia, a similar, more than 95% of pepper farms were infected P. capsici, causing 5%  - 10% of productivity decrease. And in India, foot root causes up to 30% yield loss.

        In Vietnam, the first disease recording was in the half of 20th century, in Ba Ria-Vung Tau province with devastating 390 ha of Piper nigrum. Several gardens have over 80% in death rate in North Central Coast, in some  cases 100% pepper vines died off. In the Western Highlands, similarly, average 50% of pepper farms were infected by P. capsici. The infection  level depends on investigated locations, ranging from 24.6 to 83.3%. Management of P. capsici on Piper nigrum is enormously complex and a big challenge. Meanwhile, study on this pathogen in Vietnam was limited, which leads to lack of knowledge and information. Therefore, this review aims to investigate the causes including biological characteristic of pathogen, climate and cultivations that contribute to serious infection and quick outbreak of P. capsici in Vietnam’s black pepper production.   

2. Key Elements Affecting Outbreak of Disease   
2.1. Biological Characteristics of P. capsici 

2.1.1. Morphological Details 

2.1.2. Reproduction   

2.1.3. Life Cycle 

2.1.4. Outbreak   

2.1.5. Susceptible Hosts 

2.2. Climatic Conditions

2.3. Inappropriate for Cultivated Methods 

3. Conslusion