2015021036 coconut bud rot

Caused by pathogen Phytophthora palmivora.
5-20 years old trees are more susceptible.
Symptoms - Heart leaves become brown and finally brake off.

1. COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), Via Vaigai Dam, Theni-625 562 COCONUT BUD ROT Student: Course Teacher: I.Gayathri Dr. Parthasarathy .S 2015021036 Asst. Prof., Plant Pathology.

2. COCONUT BUD ROT Causal Organism : Phytophthora palmivora (Butler)

3. HISTORY The first report of bud- rot incidence was from Grand Cayman, an island in the West Indies, in 1834 ( Tucker 1926 ). Since then Quillec et al. (1984) reported the incidence from Sri Lanka, Indonesia, the Philippines, Colombia, PapuaNew Guinea, Vanuatu, Fiji, French Polynesia and the Dominican Republic.

4. Butler was the first to identify the disease in 1907 and he named the pathogen as Pythium palmivora but later transferred it to genus Phytophthora . In 1996, heavy incidence of bud rot disease was reported from Kuttiadi , in Kerala, leading to the destruction of thousands of coconut palms in that particular region.

5. Worldwide : The disease is reported wherever coconuts are grown. It is recorded on coconut from Cook islands, Fiji, Papua New Guinea, Samoa, Tonga and Vanuatu. India : The disease is widely prevalent in East and West coasts of India. In Tamil Nadu the disease is found in Chengalpattu , Coimbatore, Cuddalore , Villupuram and Vellore districts. DISTRIBUTION

6. Systematic Position – Phytophthora palmivora Kingdom : Fungi Phylum : Heterokontophyta Class : Oomycota Order : Peronosporales Family : Peronosporaceae Genus : Phytophthora Species : P. palmivora

7. Pathogen and its characters The fungus produces intercellular, non septate , hyaline mycellium . Sporangiophores are hyaline and simple or branched occasionally. The sporangia are hyaline, thin walled, pear shaped with a prominent papillae. Sporangia releases reniform , biflagellate zoospores upon germination. The fungus also produces thick walled, spherical oospores. In addition, thickwalled , yellowish brown chlamydospores are also produced.

8. Favourable conditions High rainfall, high atmospheric humidity (above 90 percent), low temperature (18-20 o C) and wounds caused by tappers and Rhinoceros beetles ( Oryctus rhinoceros)

9. Mode of Spread and Survival The fungus remains as dormant mycelium in the infected tissues and also survives as chlamydospores and oospores in crop residues in the soil. The disease spread is mainly through air-borne sporangia and zoospores. Rainfall also helps in spreading the disease. Insects and tappers also help in the spread of the inoculum from diseased trees.

10. Symptoms The earlier symptom is the yellowing of one or two younger leaves. Black spots appear on spindle leaves.  Basal tissues of the leaf rots quickly and can be easily separated from the crown. In the later stages the spindle withers and drops down.  The tender leaf base and soft tissues of the crown will rot into a slimy mass of decayed material emitting foul smell.

11. Ultimately the entire crown falls down and the palm dies. In adult palms, the first visible symptom is the colour change of the spear, which becomes pale and breaks at the base and hangs down. The rotting slowly progresses downwards, finally affecting the meristem and killing the palms. This is accompanied by drooping of successive leaves. Even then, nuts that are retained on the palm may grow to maturity. 

12. Pale leaf Leaf rot

13. Rotting of basal tissue Drooping

14. Integrated Disease Management Cultural control Provide adequate drainage in gardens, good drainage lowers the humidity in the plantation and reduces leaf wetness, which is needed for spore germination. Cut down and burn affected trees , as soon as the disease is seen.

15. Plant palms atleast 10 m apart; wide spacing allows air movement through the plantation, and reduces the leaf wetness.

16. Resistant varieties Malayan yellow and red dwarf varieties are susceptible to bud rot, but hybrids with dwarf and tall parents are less so. The Polynesian Tall and Rennell Tall are said to have good tolerance.

17. Chemical Method Remove all the affected tissue of the crown region and crown drenching with Copper oxychloride 0.25%. Apply Bordeaux paste and protect it from rain till normal shoot emerges. (Dissolve 100 gm of copper sulphate and 100 gm of quick lime each in 500ml water separately and mix to form 1 litre of Bordeaux paste).

18. The infected tissues from the crown region should be removed and dressed with Bordeaux paste sprayed with 1% Bordeaux mixture as pre-monsoon spray (May and September). Leaf axil filling with Sevidol 8G, 25 g mixed with 200g sand is recommended to red palm weevil infestation of affected palms. Spray with Copper oxychloride 0.25% after the onset of Monsoon.

19. REFERENCES V.K.Gupta , Y.S.Paul , Satish K. Sharma, 2017, Fungi and Plant Diseases, Kalyani Publishers, New Delhi-110 002. Pg No : 262,263 vikaspedia.in www.pestnet.org https://www.drysrhu.edu.in www.ccari.res.in www.agritech.tnau.ac.in