There are countless reasons to follow the gardener’s golden rule: right plant, right place. Plants that are placed in an environment with the proper soil profile, sun exposure and rainfall will thrive beautifully with minimal extra “inputs” like fertilizer and other control products. And, this landscaping mantra extends to controlling threatening diseases.
When positioned in the right place, plants have every opportunity to grow strong on their own. When we force a flower, tree, shrub or grass to grow in conditions that are not ideal for its type, that’s when Mother Nature reminds us who’s really in charge. In fact, the three top disease threats in Kauai can be prevented by simply making smart planting choices.
Meanwhile, early detection of disease yields best treatment results. That’s why the well-trained eyes at No Ka Oi are constantly on the lookout for these diseases, and others that can develop when conditions are ripe.
Because our crews become regulars on clients’ properties, they become sensitive to plants’ health. When any change is detected, they’re prepared to act with appropriate treatment measures.
Here are three top diseases that threaten Kauai landscapes, along with how to prevent, identify and treat them.
Disease #1: Sooty Mold
Sooty mold develops when ants and mealybugs are left untreated, and these pests generally move in when plants are placed too close to buildings, under eaves or crowded with other plants.
For example, plumeria trees need lots of space, air, light and wind to stay healthy. But often, these trees are planted in environments where everything they need to grow strong is not available. Many times, plumeria trees are planted close together up against buildings.
While mealybugs can be ousted from plants using insecticides, treatment requires constant spraying—and no one likes that. Sooty mold can be virtually avoided by following the right-plant-right-place rule.
Sooty Mold Symptoms
Black growth covers leaves and blocks the sun from delivering much-needed light to the plant. This prevents growth.
Sooty mold is an eyesore in the landscape, which is especially troublesome for Kauai resort and retail properties, and other commercial developments.
Sooty Mold Treatment
An insect control program will prevent ants and mealybugs from infesting plants, which can prompt the development of sooty mold. Some general fungicides can be used to kill off the mold and prevent its spread.
Leaves of plants in especially visible locations can be washed to remove black fungal growth using diluted soapy water.
Disease #2: Fairy Ring
Many Kauai commercial property owners find seashore paspalum grass attractive. People love the grass, but they don’t realize that it can be difficult to manage when growth conditions are less than perfect. While this grass is highly salt-tolerant, which is great for beach properties and landscapes that weather lots of ocean spray, this grass does require full sun, and its tolerance to foot traffic is only fair.
Disease is more likely when seashore paspalum grass, or any plant, is placed in a less-than-ideal growing environment.
A common disease culprit on seashore paspalum grass is fairy ring. As its name implies, rings appear in the turf that destroy its aesthetic quality and overall health.
Fairy Ring Symptoms
The characteristic rings formed by fairy ring result from fungi that causes bands of turfgrass to turn darker green and grow more quickly than the rest of the lawn. Mushrooms may also crop up in diseased grass. Rings may extend several inches to a foot wide, and up to 60 feet in diameter. They can overlap, producing scalloped edges of grass that dies out. Mushrooms, toadstools and puffballs can form along the circular bands if soil is particularly moist.
Fairy ring can emerge in these conditions: stressed or undernourished turf; when warm, moist weather is followed by a dry spell; excessive irrigation; poor soil quality (soil not receiving enough air).
Fairy Ring Treatment
Fungicide applications can suppress fairy ring after the diseased lawn is properly aerated to allow air, water and treatment to penetrate the grass and reach diseased roots and soil.
Unfortunately, fungicides are not always effective and fairy ring can result in a damaged lawn that requires complete renovation.
That’s why it’s important to plant the appropriate grass type for your Kauai microclimate and to adopt cultural practices (proper mowing, watering, aeration) to avoid disease.
Disease #3: Plumeria Rust
Plumeria is a favorite plant in Kauai, but it may be susceptible to the powdery, yellow orange lesions that can develop on leaves with a disease called plumeria rust.
This can cause leaves to turn brown and fall off the plant within a couple of months, a disappointing (and costly) loss for Kauai commercial property owners, who look forward to plumeria’s fragrant blooms.
Planting in dry, less humid areas can reduce disease susceptibility, and there are plumeria cultivars available that are more disease-resistant.
Plumeria Rust Symptoms
Plumeria rust can first appear as yellow flecks on the leaf surface. Underneath are lesions bearing spores. As the yellow spots coalesce, they become sunken, angular, grayish-brown spots. Leaves in advanced stages of the disease may dry, curl and fall off the plant.
Plumeria rust can result in complete defoliation of the plant.
Plumeria Rust Treatment
Plumeria trees should be given plenty of access to air and light—room to grow. So avoiding overcrowding is important for staving off plumeria rust.
Preventing tall weeds from growing near plumeria trees can increase airflow to the plant and reduce humidity. Plumeria rust can be treated with fungicides.
Let No Ka Oi Help You Choose The Right Plant
We know that healthy landscapes begin with smart plant choices. At No Ka Oi, we work closely with Kauai property owners to help them select grass, flowers, trees and shrubs that will thrive on their properties.
Preventing disease begins with creating a solid foundation for the landscape. Let’s talk more about how you can establish a disease-resistant landscape.
Call us any time at 808-335-5887, or fill out our simple web form, and we’ll get in touch with you!