What is eating my palm trees

[Anthony5]

I have 3 palm trees ( actually 3 sets of 3) that are looking pretty bad for the past 6 months or so.

I have repeatedly sprayed them with all kind of insecticides but to no avail. Two of them have slightly recovered, but one has completely died.

It just rots away as you can see in the pictures. I cut one trunk after it was empty for about 20 cm from the top, and it had some kind of large black ant inside, although dead.

That was last week, but you will see in the picture that the cut off trunk has further deteriorated in the mean time. I can't see any insects at the time.

Advice appreciated.

[rice555]

Beatle! Dr Treelove has a great post about the beetle problem with palms/coconut palms.

You have to inject the treatment to kill them, sprays DON"T work.

rice555

[Anthony5]

Beatle! Dr Treelove has a great post about the beetle problem with palms/coconut palms.

You have to inject the treatment to kill them, sprays DON"T work.

rice555

Can you give a link to that post please as I can't even find dr treelove as a member on this forum.

[MJCM]

Found it I think

http://www.thaivisa.com/forum/topic/435037-bug-attack/#entry4169494

[Anthony5]

Found it I think

http://www.thaivisa.com/forum/topic/435037-bug-attack/#entry4169494

Thanks for the link, but in there they speak about a beetle, from which I don't find any traces. I find a single large black ant in the trunk I cut off. I've also use imidicloprid and cypermethrin on it several times.

I was also from the impression that none of the 3 trees had grown since I planted them, and I just found a picture from one of them taken May 2012.

The second picture is taken 30 months ago.

Edited December 13, 2014 by Anthony5

[rice555]

Found it I think

http://www.thaivisa.com/forum/topic/435037-bug-attack/#entry4169494

Thanks for the link, I was heading out the door when I posted, and got my remedies crossed.

My pic's were from a coconut that went tits up, use to have lots of fruit. The top fell off one day and 6 months later half the trunk fell. The last part of the trunk fell a few days ago when

the wife had a guy cutting grass last week and it fell when he pushed hard, the second pic, the

inside is like coir, no fiber like you get when you cut a palm.

Thanks.

rice555

[xen]

Another cause you could explore if you have not seen any physical beetles or insects is phytophthora (Phytophthora cinnamomi ). It is affecting many plants including phoenix species of date palms and other palms . It is essentially a root rot but it interferes with the flow of nutrients between the root system and the foliage and when the crown dies it is all over for the palm. Stem rot is an indication of phytophthora but after it is too late.

Here is a link from the Royal Botanic Gardens : http://www.rbgsyd.nsw.gov.au/plant_info/pests_diseases/fact_sheets/Phytophthora_dieback.

There is a lot of other information on Google.

It may not be without knowing other factors but i tend to look for environmental factors whilst looking for insects . Often insect attack is a secondary problem as they will attack an weakened plant from environmental factors.

[Anthony5]

Another cause you could explore if you have not seen any physical beetles or insects is phytophthora (Phytophthora cinnamomi ). It is affecting many plants including phoenix species of date palms and other palms . It is essentially a root rot but it interferes with the flow of nutrients between the root system and the foliage and when the crown dies it is all over for the palm. Stem rot is an indication of phytophthora but after it is too late.

Here is a link from the Royal Botanic Gardens : http://www.rbgsyd.nsw.gov.au/plant_info/pests_diseases/fact_sheets/Phytophthora_dieback.

There is a lot of other information on Google.

It may not be without knowing other factors but i tend to look for environmental factors whilst looking for insects . Often insect attack is a secondary problem as they will attack an weakened plant from environmental factors.

After reading the article I clearly see some similarities. Especially because the effected trees are in an almost always most area. They suggest to use a fungicide that contains potassium phosphonate.

Any suggestion of a specific fungicide I should look for in the farm shop?

[xen]

You can use fungicides as a short term strategy . Sorry i can't help you in recommending anything as i don't really know what is available locally , but potassium phosphate and calcium phosphates have been used since the seventies . However once you have Phytophthora it remains in the soil . But i would be looking at drainage and aeration as long term solutions , but this may not help your palms in time for them to be saved . Perhaps if it a clay soil use some gypsum and or increase both sand and organic matter. Also avoid using fertilizers containing nitrogen as this just feeds the phytophthora. I would guess you use a fair bit of fertilizer to get that turf lawn looking as good as it does.

Incidently i really like that wall in your first photo. Very nice work .

[Anthony5]

You can use fungicides as a short term strategy . Sorry i can't help you in recommending anything as i don't really know what is available locally , but potassium phosphate and calcium phosphates have been used since the seventies . However once you have Phytophthora it remains in the soil . But i would be looking at drainage and aeration as long term solutions , but this may not help your palms in time for them to be saved . Perhaps if it a clay soil use some gypsum and or increase both sand and organic matter. Also avoid using fertilizers containing nitrogen as this just feeds the phytophthora. I would guess you use a fair bit of fertilizer to get that turf lawn looking as good as it does.

Incidently i really like that wall in your first photo. Very nice work .

Thanks, lot of people commend on that wall.

My soil does indeed contain much clay I suspect, but in one way it is an advantage as I don't have to water it too much, since it stay wet easily.Maybe too wet?

I spray before dawn for 7 minutes, and by the evening the soil will still be wet. I spray again around 5pm for 4 minutes, since I worry that the grass will dry out otherwise.

I fertilize maybe 4 times a year, using 15-15-15, at a 1 kg per 100m² rate, so I don't think that is excessive.

As I said, about 6 months ago the palms looked much worse, so they have recovered to some extend, though one has completely died.Will have to dig it out in the next few days.

If you compare the growing rate of the tree in my last post, is it normal it grows that slow or does this indicate problems. There is 30 months between both pictures.

[drtreelove]

I suspect that Xen is on the right track, that this is not an insect pest problem, like beetles, but a water mold (phytophthora) or fungal root rot or stem infection. The beetle infestations usually start from the foliar tips or frond bases and work their way down. I think Xen may be right that it is related to the growing conditions, poor drainage and that you should concentrate on the soil and water management aspect. Fungicides may not help if the growing conditions are poor.

Many species of palms and trees cannot take frequent irrigation where it never dries out between watering. Sometimes it takes several years for trees to develop signs and begin to decline, therefore people don't realize the damage that is being done below ground in the roots and root crown from excess water. This is one of the most frequent problems that I see when called on to diagnose plant problems, especially where irrigation sprinklers hit directly on the tree trunk and/or root collar at the base. Except for a few species of water loving trees and shrubs, most woody plants are not compatible with lawns. The frequent watering that grasses require is contrary to best growing conditions for most woody plants. See the book "Golf Course Tree Management" for more details of why this is an important consideration. http://www.amazon.com/Golf-Course-Management-Sharon-Lilly/dp/1575041170

Best growing conditions for trees is in planting areas outside of lawn areas and with separate irrigation cycles that can be programed and monitored for appropriate soil moisture levels according to season and rainfall. For most woody plants it is best to irrigate infrequently and deep, then allow the soil root zone to dry out somewhat before watering again. When it stays muddy-wet is when certain disease organisims like Phytophthora cinnamomi that Xen mentions, and other pathogens flourish.

You may consider digging out the palms and replanting in a raised bed or mounded area, to create better growing conditions. When you do this you can amend the soil appropriately.

It's difficult to amend soil in an established lawn, because you just can't rototill in the bulk organic matter and mineral amendments needed, it has to be a process of adding what you can, in the amounts that you can, considering the conditions.

Or the more drastic measure is to remove the existing lawn and do a proper soil preparation before re-planting.

The most comprehensive way to know what is needed without just guessing, is to collect a soil sample and have it laboratory tested, then apply mineral and biological amendments based on actual deficiencies found.

At least your palms don't appear to have soil piled up at the base of the stems, but along these lines I might mention that this is one of the most potentially damaging, poorly advised local practices. Woody stems should be above soil grade and be allowed to dry out, without moist soil or mulch piled up against what is supposed to be above ground wood. Root tissue can take more soil moisture, in most cases it is not the same kind of tissue as woody stems.

Edited December 26, 2014 by drtreelove