Tree Bean (Parkia Roxburghii) declined in Mizoram

Tree bean (Parkia roxburghii) is economically important multipurpose fast growing deciduous leguminous tree vegetable of Mizoram and other northeastern states of India. It is distributed in India, Bangladesh, Myanmar, Java, Thailand, Egypt and the Malaysian region. In NorthEastern India, tree bean is found growing wild throughout the region. It is known as Zawngtah in Mizo language and the trees are mostly grown in jhumland, roadside, orchard, and backyard garden. Almost every part of the plants an i.eflower, tender leaves, tender pods and mature seeds are eaten as vegetables and provide a good source of nutrients. The mature seeds are useful against food allergy, diarrhea and dysentery. Traditionally, the bark and fruits are prescribed to check excessive bleeding during menstruation and the juice of the green rind of the pod is applied to fresh cuts, scabies and itching. In addition, the seeds are eaten by various wild animals and birds. The matured pod is one of the delicacies of the tribal people of the region and fetching high market price. Tree bean decline have been frequently observed in Mizoram since 90’sbut since the sudden death have been confined in few locations, no proper studies on the decline have been carried out. Thangjam 2006 reported that the problems of die-back symptoms in P. timoriana have also been found to be associated with the infestation of Anoplophora glabripennis (Motchulsky) commonly known as Asian longhorned beetle and Recently, sudden decline of tree bean was reported from various parts of Manipur, Nagaland, Mizoram and Meghalaya, which seriously affected the socio-economic situation of the growers (Thangjam and Sahoo 2012). Preliminary investigation on the reasons behind the decline of tree bean was carried out during 2012-2013 in all the Krishi Vigyan Kendra of Mizoram under the direction of Director of Agriculture (Research and Education), Government of Mizoram but no proper conclusion was made. Recently, it was found that the sudden death or decline of tree bean in Mizoram was frequently associated with pathogen identified as Botrydiplodia theobromae and also some small unidentified bark borers infesting the tree (Ratankumar Singh et al 2018). In Manipur, tree bean decline was linked to insect stem borer, Bactocera sp. (Surendranath, 2007). Rajesh et al 2012 reported Verticilium dahlae causing seedling wilt of tree bean. Thangjam et al 2003 reported that C. cautella infested tree bean plant in both field and on storage conditions and the larvae was found to feed voraciously on the green kernels. All the stages in the life cycle of the insect were observed on P. timoriana. Sinha et al 2017 reported Lasiodiplodia theobromae causing dieback in tree bean decline in Northeast India. Roy et al 2016 reported a large number of insect pests like; Asian long horned beetle (Anoplophora glabripennis); bark eating caterpillar (Indarbela spp); jassid (Empoasca kerri); aphid (Aphis craccivora); thrips (Scirtothrips dorsalis); green stinkbug (Nezara virudula); Coreid bug/tur pod bug (Clavigralla gibbosa); spotted pod borer (Cadra cautella) to be associated with the tree bean. Out of these, Asian long horned beetle, bark eating caterpillar and spotted pod borer are most commonly found associated with declining trees. Moreover, Verticillium wilt and collar rot have also been observed in declining tree bean plantation. There were reports on large scale spread of Verticillium wilt from Chandel district of Manipur. Collar rot (Phytophthora sp.) has been found in valley areas, especially in Imphal West and Bishnupur district of Manipur. (Roy et al., 2016). Diseases and pests Parkia species have a number of pests in common with other leguminous trees and shrubs. The stem and bark borers Xystrocera festiva and Cossus subfuscus can cause severe damage in Parkia speciosa, especially at lower elevations in Java. Other pests are the pod borers Cryptophlebia ombrodelta and Mussidia pectinicornella, and the caterpillars of the leaf feeders Polyura hebe, Eurema blanda and Eurema hecabe. The seeds are relished by a great number of arboreal mammals (Yusuf et al., 2001)