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August 2016. An email from the ICAR-Indian Institute of Oil Palm Research. Can any body tell the reasons for the crown collapse that has occurred on these oil palm plants. The symptoms have become common in many oil palm areas of Andhra Pradesh where the majority of the plantations exist. Mostly the symptoms are seen after a severe summer season, but there does not seem to be a correlation between heavy wind and rains. The intensity of the symptoms was similar on young as well as old palms.
If its the red palm weevil (Rhyncophorus ferrugineus) the palms should be chopped down as soon as possible at the larvae are in them, and the damage will spread. The symptoms were similar to R. ferrugineus attack.
CABI said that they have records of Rhynchophorus vulneratus on sago but not aware of any red palm weevil attacking the crop.
Other causes suggested were red ring caused by a nematode, and upper stem rot due to Ganoderma but, as both on young and old palms have symptoms, this is unlikely.
Later, more information was supplied as follows. The problem has been occurring since 1998. It first started as leaf breaking/bending at the base of the petiole. Tested for the presence of microbes but find anything. These leaves continued to hang from the crown for several months, but still green. For some years the problem was not seen, but in recent years, particularly during the periods of drought with high temperatures, this particular problem is visible.
We could not find a single red palm weevil or rhinoceros beetle in these palms. In fact during my 21 years of service on oil palm, I have never seen seen a single red palm weevil damaged oil palm, though they were found on the bunches.
Fusarium problem was observed on few palms but it was Fusarium solani but not F. oxysporum. Prevalence of this fungus and mortality of the palms was observed more on Blue latan palms rather on oil palm. However, in this case leaf drying before breaking was observed which is not what happens with the present disorder.
Most of these palms are showing boron deficiency. In some cases, the symptoms were severe, but whether there is any relationship between boron deficiency and breaking of the fronds is not clear.