University-trained extension master gardeners routinely put themselves in the hot seat while fielding an array of home-gardening questions via phone and email help lines and at Plant Doctor clinics in the community. Sometimes the questions clearly describe a very distinct and common problem that yields a quick, certain identification and solution from the master gardener. In other cases more information is required to help narrow down the possibilities. This line of inquiry can include photos via email or bringing plant/pest samples to the volunteers.

In still other instances further diagnosis is required and laboratory analysis is recommended for exact pest identification (such as disease-causing fungi) or to rule out soil problems due to extreme pH or high salinity, for example.

Here are two questions recently received by West Hawaii Master Gardeners at the Kona Extension Office that illustrate these scenarios. The answers are provided courtesy of master gardener Dawn Velasquez.

Question: I have Keitt mangoes that are being invaded by an insect. There is a small black spot on the bottom of the fruit, and when you open it the seed is black and some of the flesh, too. What do you think it is, and how do I get rid of it?

Answer: From your description and without seeing pictures, our first suggestion would be that you have mango seed weevils. We recommend doing a Web search for this pest to see if the photos and description match your problem. Adult females lay eggs on the surface of young mango fruits. The larvae bore through the fruit and into the soft, developing seed, where they stay until the fruit reaches maturity. They then emerge as adult weevils, leaving behind damaged flesh and a destroyed seed.

Because the insect is protected by the growing fruit, pesticides are not recommended for home gardeners.

The mango seed weevil is host-specific and a poor flier, so the biggest source of infestation is dropped fruits or seeds on the ground in which weevils can survive nearly 10 months. Therefore, regular removal and destruction of all ground fruit and seeds up to the end of the harvesting season is important and effective.

Q: We have two palms that look like coconut palms but do not bear coconuts. I think they are called window palms. One of them has appeared droopy for the past month or so, and a lower frond actually broke off last week. We have fertilized and also used Epsom salt. The other palm’s new fronds stick up instead of drooping, but it does have a lot of these brown spots — more spots than the droopy palm. What I should do?

A: Judging from the photos you sent, the spotting and browning on the leaves indicate they may be suffering from potassium deficiency. These symptoms will appear first on the oldest leaves (the lower third of canopy). Palm-specific fertilizers are high in potassium due to their susceptibility to this nutrient deficiency. Lawn products and poisons can certainly hurt the palms, but if you haven’t changed anything in your lawn care program over the last couple of years, then it seems unlikely the trees would suddenly suffer. Are there any other external factors that might be unusual?

Another thing to check for is pencil-size holes in the frond stems or trunk that would indicate a boring-type insect such as the sugar cane weevil. Inspect the crown especially thoroughly.

Slight sagging or drooping of palm fronds is also an early symptom of a fatal stem-rotting disease of certain palms, especially coconut, caused by the fungus Thielaviopsis. To properly diagnose the problem, you should bring a sample to your local University of Hawaii Cooperative Extension Service office and possibly submit it for laboratory analysis.

We are in the Kona office every Thursday from 9 a.m. to noon to answer emails (konamg@ctahr.hawaii.edu) and phone calls (322-4892).

Ty McDonald is a University of Hawaii extension agent and Master Gardener coordinator at the Kona Extension Office. Email him at tym@hawaii.edu.