Occurrence and Distribution of Coconut Diseases in Tamil Nadu, India

Abstract

Coconut is an important plantation crop with many decades of life span ,suffers from numerous diseases incited by fungi ,bacteria, virus, viriod and phytoplasma leads to drastic reduction in yield. Roving survey was conducted in five major coconut growing districts of Tamil Nadu viz., Coimbatore, Tirupur, Theni, Tirunelveli and Kanyakumari districts during 2014-2019 for assessing the incidence of important diseases of coconut .The fungal diseases viz., bud rot, basal stem rot, stem bleeding, leaf blight and leaf spot and phytoplasma disease viz., root (wilt) are the widely prevalent disease in these districts. The highest bud rot incidence of 7. 7% was observed in Pongalliyoor village in Coimbatore district and basal stem rot incidence (35.29%) in Manupatti village, Tirupur district . The prevalence of stem bleeding was found to be sporadic and the high incidence of 12.0 % was observed in Therichanamkoppu village, Kanyakumari district. The highest mean district incidence of bud rot, basal stem rot and stem bleeding was registered in Tirupur district which were 1.40 %, 2.59% and 4.94 % respectively. The severity of leaf blight was more (32.0 PDI) in Thanthoni, village, Tirupur district and the leaf spot (25. 5 PDI) in Kaliapuram village, Coimbatore district and the district mean incidence of leaf blight was highest (20.19 PDI) in Tirupur district and leaf spot (10.1 PDI) in Theni district. The maximum incidence (37.25%) of root (wilt) was noted in Gudalore village, Theni district and the district wise average was high (21.1%) in Theni district. The state average of the surveyed district for bud rot, basal stem rot , stem bleeding, leaf blight, leaf spot and root (wilt) incidence ranged from 0.09-0.60%, 0.44-1.03 % , 0. 1 -1.05% 4.9 -8.52 PDI, 2.55 to 6.55 PDI and 5.6-10.3% respectively.

Scenario of fungal leaf spot and leaf blight diseases in coconut and arecanut

“…It is reported that at Vepangulam, Tamil Nadu disease intensity in East Coast Tall coconut was maximum in December (40.5 %) and minimum in June (23.9 %). Surveys conducted by Esakkimuthu et al (2020) in Tamil Nadu showed that Avalchinnampalayam, Angalakuruchi and Kalliyapuram villages of Coimbatore district had maximum disease incidence and the severity was more in dwarf varieties compared to tall varieties. Study conducted in plantation crop based cropping system plots of Wayanad district of Kerala to assess different diseases for their incidence during different seasons revealed that in Coconut, grey leaf blight was found to be the most severe one with a disease incidence of 98.6% incidence during NE monsoon (John et al 2011).…”

“…Johnson et al (2014) reported that Lasiodiplodia has become a major problem in coconut growing districts of Tamil Nadu viz., Coimbatore, Erode, Dindigul, Tirunelveli and Kanyakumari which lead to yield reduction of 10-62(1) March, 2024] Keerthana Jayarajan and others 25%. The disease is endemic in Sencherimaali, Thanthoni and Karapadi villages of Tirupur district and Odayakulam and Kaliapuram of Coimbatore district (Esakkimuthu et al 2020). Survey conducted by Neeraja et al (2020) in West Godavari and East Godavari districts of Andhra Pradesh indicated that the disease incidence was more in Jangareddygudem village of West Godavari (25.8%) and in Mamidikuduru village of East Godavari (25.5%).…”

“…The symptom first appears on outer whorls, as small yellow spots with dark brown margin, which gradually turn in to brown with greyish centre. The spots eventually coalesce to form blighted appearance (Chinara, 2012;Rajeswari et al 2020). On adaxial surface of leaves, rectangular, ovoid, globose or spherical black pycnidia are produced (Iyer et al 2018).…”

“…Lasiodiplodia leaf blight of coconut is one of the economically important fungal diseases in Brazil (Monteiro et al, 2013). Symptoms of the disease appear on the leaves of outer whorls, usually start from the tip and then the fungus systemically invades the rachis resulting in complete drying of the leaves and reduction of photosynthetic area (Neeraja et al 2020;Rajeswari et al, 2020;Santos et al, 2020). As a consequence, leaves exhibit a burnt appearance and leaves of outer whorls of the palm fall off.…”

Potential of Omics to Control Diseases and Pests in the Coconut Tree

“…The nuts become desiccated, shrunken, deformed and dropped prematurely. In the leaves, this pathogen causes the disease "leaf blight", drying leaves from tip downwards, inducing a charred or burnt appearance, more evident on lower fronds [25]. Lasiodiplodia theobromae causes significant monetary losses in the coconut industry in India.…”