Sunday | July 24, 2016
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Garden Guy: Rats can be a nuisance around home

(Picture sent of orange fruit hanging on tree partially hollowed out). I thought it might be a rat. Caught one, but can’t catch any others. Whatever it is, it eats the oranges before ripe and hollows them out. Sometimes there are bugs in the oranges, but not sure if they are just scavengers on partially eaten oranges.

Hollowed out oranges, hanging on the tree or on the ground, are definitely signs of rat feeding. There are four rodents in Hawaii that can actually cause economic hardship: the roof or black rat, the Norway or brown rat, the Polynesian or Hawaiian rat, and the house or field mouse.In addition, they are carriers of contagious diseases including plague, murine typhus, leptospirosis, and salmonellosis. Rodent control is not easy due to their ability to adapt to changes and their capacity to reproduce.

Rats are nocturnal. They have excellent memories and very repetitious habits.

They are easily frightened of new things placed in their environment. The roof rat is most pronounced in this tendency. Rats have a keen sense of smell and hearing, and only a fair sense of sight with the ability to see in the dark.

Besides the hollowed out oranges, common signs of rodents are droppings, rubmarks, gnawings, nests, and unpleasant odors.

In controlling these pests around the home, the first step is to clean up the environment by removing accesses to food and shelter. Physical barriers such as screens may need to be installed. When only a few rats are involved trapping can

be effective. For field problems, secure snap traps to limbs and bait with raisins, citrus or other fruits. Traps should be baited and left unset until bait is readily consumed.

Paraffin-type bait blocks containing anticoagulants are very effective in controlling rats. They appeal to the rats gnawing instinct, especially those blocks with numerous ridges. Baits should be replaced immediately as they are eaten, since only a single feeding on the first generation anticoagulants (diphacinone) will not control rats. Baits must be eaten over a period of several successive days.

For safety, baits other than blocks should be placed in bait stations. For outdoor infestations, the blocks can be secured to limbs six feet or more above the ground, out of reach of children and dogs.

Some poisons have a secondary effect which will affect animals which consume dead or nearly dead rodents. Thus, it is imperative that strict safety precautions be used in the placement and disposal of poison baits for rodents.

Are you familiar with bacterial blight of anthuriums? What treatment do you recommend? Are all anthuriums subject to the disease? Thank you for your time.

Bacterial blight of anthurium is a very difficult disease to control. It is systemic within the plant. The bacteria can be spread by propagation material, tools, mud from shoes and even wet clothing brushing up against infected leaves. Every effort needs to be made to eradicate the disease from the property, or at least, to contain it so it does not spread to other areas.

Here are some things to do:

1. Remove all infected plants and burn, bury or bag them.

2. Beds or areas that are infected need to remain fallow for at least two months before replanting.

3. Plant using only disease free material.

4. The bacteria is spread by water droplets, either rain or irrigation water. Thus keeping plants under cover as much as possible will help slow the spread of the disease.

There is varying susceptibility of this disease among anthurium cultivars. The UH Extension Service publication “Bacterial Blight of Anthurium” by Wayne Nishijima notes the response of different cultivars to the disease.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at You also can visit his website at


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