The symptoms do not look like ‘freckle’ that is caused by the fungus Cercospora elaeidis and is found mostly in nurseries, this disease occurs mainly during the middle and at the end of the dry season. The fungus is present in Central America and in West African oil palm growing countries and has been recorded in Tanzania but is not found in SE Asia including Viet Nam.
There are other fungi that can cause leaf spots similar to those in your pictures. These have been known to cause considerable problems in oil palm nurseries, examples are -Helminthosporium, Bipolaris, Curvularia, Drechslera, these fungi tend to cause lesions that have a halo around them that can be very pale or become yellow-orange in colour. The taxonomy of these fungi has changed considerably over the years and so searching the literature for the palm diseases they cause can be confusing and frustrating sometimes. Poor nutrients in nursery polybags; growing in peat soils; uneven watering; bags too close together creating a microclimate suitable for the fungi to spread easily can contribute to the spread of these nursery diseases. Polybags should be big enough for the palm to grow from a germinated seed to a plant between 9-12 months old when they will be ready for transplanting into the field. Planting into a small bag and then replanting into a bigger bag gives more opportunity to damage the young palms and damaged plants are more susceptible to these nursery diseases.
Most of these diseases do not respond well to fungicide application and to be perfectly honest spraying is often a waste of time and money. Chemicals should be a last resort and then only if you are sure they will be effective.
I suggest sanitation and hygiene as a way to control this problem. Make the rows wider for the polybags still in the nursery so that the fronds do not touch the fronds of another young palm. Do not spray water over the fronds, only water straight into the polybags. When was the last time the nursery palms had fertiliser? They may need an extra dose of fertiliser but be careful not to give them too much as you do not want the nursery palms to produce too many new fronds too quickly. Badly infected nursery palms must be removed and destroyed, either bury or burn them, do not leave them at the edge of the nursery field as they will be a source of infection.
Sometimes young palms suffer from transplanting shock and what may have been a few small insignificant lesions in the nursery can become a problem for newly planted out palms. These palms should recover given time, however if there are a lot of dying or dead fronds these should be removed. Oil palm is a resilient plant and with a bit of extra care and attention they should recover.
Where in Viet Nam are you based? I would be most interested in knowing as some years ago I worked with NIPP in Ha Noi and SOFRI in My Tho as well as teaching courses at universities in Ha Noi and Can Tho.
I hope this reply goes someway to help solve your problem, please ask if you have further questions.
Thanks for providing such detailed images - this should really help our community in diagnosing the disease over 10 years ago.
It was suggested to me that this might be a nutrient deficiency. You said that you thought this was anthracnose leaf spots caused by Colletotrichum gloeosporioides or leaf blights caused by Fusarium
Is there any chance it could be a nutrient deficiency?
over 10 years ago.
oh, it could be a nutritional deficiency. I hope it's true. we can overcome this condition by adding fertilizer over 10 years ago.