Question: My neighbor and I are experiencing a strange development with Manila palms growing in our yards in Kailua. For many weeks the green palm leaves have been breaking off and dropping to the ground. This is not the normal aging of the fronds, which get old, turn brown and fall. These fronds appear healthy, but dry and fall before turning brown. I don’t think dry weather can be blamed, as in past years we have had dry spells and have never seen anything like this. Can the Department of Agriculture provide an explanation?
Answer: The state Department of Agriculture received a similar complaint from a homeowner in the Coconut Grove neighborhood of Kailua in mid-June and traced it to rats.
Staff members went out and collected samples of dying palm fronds, as well as of rat droppings.
"They determined that it is a rodent problem because they found rodent chew marks on the frond stalks and lots of rodent droppings or pellets along with the marks," said plant pathologist Mann Ko.
From the shapes and sizes of the pellets, they identified the rodents as roof rats, he said.
Ko said the homeowner had fruit trees around the yard that dropped fruit, attracting rodents to the area.
Apparently, some of the rodents preferred palm frond stalks not only for food, but also for sharpening their teeth, he said.
Bernarr Kumashiro, an entomologist with the department, agreed that rats are likely the culprits, saying that in one of the photos you provided, "You can see some gnawing residue (green sawdust)."
Kumashiro advised you to look for rat droppings to confirm the determination.
"It seems like rats go for plant material in times of drought, and food is scarce," he said. "I have seen them gnawing at haole koa bark also, and Panax shoots seem to be a favorite."
But in this case, if rats are involved, damage to the fronds does not kill the trees, he said.
The homeowner who contacted the Agriculture Department was advised to clean up the area and take sanitation steps to control the rodent population using information from the state Department of Health’s Vector control pamphlet, Ko said. (See 1.usa.gov/1C3yzf5.)
Ko said the homeowner also was referred to the state Health Department’s Vector Control Section and the city’s Storm Drain Rodent Control Section.
But according to the Storm Drain Rodent Control Section, rodents are a prevalent problem in Kailua that is hard to control because they follow the storm drains from a distance, roaming around for food, he said.
In addition to rats, Kumashiro said, the dry weather still might be a factor.
"It appears that the top of the trees are showing signs of ‘bunching,’" he said, adding that he’s noticed this happening to the Manila palm in the back of his house, which is on a slope and gets no watering.
"I blame this on drought because when it rains again it recovers," he said. He also said he noticed bricks covering the ground in another one of your photos, so maybe the trees are not getting the water they need.
Mahalo
To Dennis Kam of Kahaluu and his son, Derek, who helped rescue a senior after I was pinned by a rubbish cart on a recent Sunday. I was trying to push the cart up my sloping driveway when it started to roll back, coming down on my hand and pinning me down. Fortunately, they came to my rescue. They were my angels because if they hadn’t been driving by, I don’t know how long I would have been stuck. Mahalo also to my cousin Sharon Hockridge, who took the time to drive me to the ER, wait for me, then see that I got home safely. — Linda Suzuki
Mahalo
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— Vicky Ward
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