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CURATIVE AND PROPHYLACTIC CONTROL OF FUNGAL LEAF ROT COMPLEX IN ROOT (WILT) AFFECTED COCONUT PALMS IN INDIA N. Srinivasan; M. Gunasekaran
International Coconut Community Journal Vol 19 No 01 (2003): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v19i01.365

Abstract

Root wilt disease (RWD) is a debilitating malady of coconut in India that is caused by phytoplasma. In RWD affected palms, leaf rot disease (LRD) is commonly superimposed. The LRD is due to fungi and this leaf rot phase forms an integral part of RWD complex. Control of LRD is important as it severely disfigures the palm and brings about rapid deterioration in its health and productivity. Control trial involving Phytosanitation of young leaves, pouring of broad spectrum - systemic fungicide, Contaf 5 E (Hexaconazole 5% EC) into the axil of spindle leaf besides a number of other measures was conducted to study their ameliorating effect on LRD. Prophylactic control trial, especially with the broad-spectrum fungicides was also conducted. Pouring of Contaf into the axil of spindles along with phytosanitory measures on the spindle and other young leaves significantly reduced the incidence of LRD in newly emerging spindles effecting cure. Application of the fungicide on RWD palms prior to the onset of LRD, offered prophylactic protection to emerging leaves against LRD. Relevance of practising integrated control measures, cure of LRD at an early stage itself, the need for strict adoption of crop management technology etc. for effective disease control are highlighted here.
Incidence of leaf rot disease in relation to root (wilt) in young coconut palms and fungi in lamina and petiole lesions N. Srinivasan
International Coconut Community Journal Vol 20 No 2 (2004): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v20i02.390

Abstract

Coconut leaf rot in association with root (wilt) is widespread in southern districts of Kerala, India. The disease complex has spread to northern districts of the state and also adjacent districts in Tamil Nadu. Where as the root (wilt) is a systemic infection (due to phytoplasma) the leaf rot is a foliar syndrome due to fungi (Colletotrichum gloeosporioides, Exserohilum rostratum, Fusarium spp.). Occurrence of leaf rot has been related to the incidence of root (wilt) and its appearance in young palms remained a matter of contention as to which disease precedes the other. Leaf rot lesions do occur on leaf petiole/mid-vein/mid-rib even as the disease lesions are known to be common on lamina (spindles). Investigations brought out that in majority of leaf rot affected young palms (2-5 years old) the flaccidity symptom of root (wilt) could be also discerned. In lesser number of affected palms, the other symptoms of root (wilt), yellowing and marginal necrosis, were also visible. As such, in 88.5% of leaf rot affected young palms one or the other symptom of root (wilt) has been recorded irrespective of season. C. gloeosporioides, E. rostratum and other fungi were found both in lamina and petiole lesions in different months. C. gloeosporioides was detected from petiole and lamina tissues in all the months, followed by E. rostratum, Fusarium spp. etc. C. gloeosporioides was isolated from these parts in more numbers and consistently during January-December. E. rostratum appeared erratically. Aggressiveness of C. gloeosporioides during months of wet season was confirmed. Fusarium spp. was isolated predominantly from these parts in dry months (January-May). Knowledge on occurrence of leaf rot in young palms in relation to root (wilt) and dynamics of leaf rot pathogens in leaf parts among months/seasons of year (in inoculums build-up, spread and dissemination) are important in the context of integrated management of root (wilt)-leaf rot complex.
IDENTIFICATION OF COLLETOTRICHUM GLOEOSPORIOIDES, EXSEROHILUM ROSTRATUM AND GLIOCLADIUM VERMOESENI ASSOCIATED WITH LEAF ROT DISEASE OF COCONUT IN INDIA N. Srinivasan; M. Gunasakeran
International Coconut Community Journal Vol 10 No 01 (1994): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v10i01.276

Abstract

Leaf rot is a common disease predominantly superimposed on root (wilt) affected coconut palms in India. Three fungi implicated in the disease have been found to be Colletotrichum gloeosporioides, Exserohilum Yostratum and Gliocladium vermoeseni. The cultural characters and morphological features of these fungi have been deBcribed. The pathogenic role of these fungi has been confirmed. The three fungi independently induced symptoms leading to leaf rot. E. rostratum developed the disease symptom relatively faster. Pin prick injury in leaf pieces generally favoured the fungi in infection and had pronounced effect for G. vermoeseni.
FIELD CONTROL OF LEAF ROT DISEASE OF COCONUT WITH FUNGICIDES N. Srinivasan; M. Gunasekaran
International Coconut Community Journal Vol 12 No 02 (1996): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v12i02.303

Abstract

Leaf rot is a disease of fungal complex super imposed on root (wilt) affected coconut palms in India. A field fungicidal control trial on the disease involving contact (indofil M‑45, Fytolan) and systemic (Calixin) fungicides was conducted Fungicidal treatments, spraying of Indofil M‑45 and pouring of Calixin into axil of spindle, were found beneficial as the disease intensity reduced in newly emerged leaves. However, the extent of disease amelioration by fungicides was marginal to moderate level only. Importance of broad spectrum fungicide(s) and measures of disease protection are outlined.
COCONUT LEAF ROT DISEASE COMPLEX A REVIEW N. Srinivasan; M Gunasekaran
International Coconut Community Journal Vol 15 No 01 (1999): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v15i01.323

Abstract

Occurrence of leaf rot disease (LRDC) of coconut is related to increased incidence of root wilt disease (RWD). The palms with RWD irrespective of age are susceptible, young ones are more susceptible to LRDC. Tender leaves especially the spindle play a critical role in LRDC incidence and the disease attributed to fungal complex. Among the 14 species of LRDC Angi, several were proved to be pathogenic; Colletotrichum gloeosporioides (Penzig) Penzig and Sacc and Exserohilum rostratum (Drechsler) Leonard and Suggs are discerned as the main pathogens. C. gloesporoides was aggressive during monsoons and positively correlated with rainfall and relative humidity (11% RH, whereas Erostratum less strongly correlated Fusarium spp. predominated in dry seasons. Importance of microclimate, survival and quiescence of the pathogens are to be determined. Diagnosis of RWD by techniques such as PCR and understanding the molecular basis of vulnerability of palms to LRDC would help to initiate early control measures. Planting of RWD cum LRDC resistantl tolerant varieties after eradicating the RWD infected palms is desirable. Protection ofyoung leaves by chemical or biocontrol agents or a combination of both with phytosanitation is important. 4 system approach with integrated measures needs to be utilizedfor sound management of LRDC.