Slaters are not insects. They are crustaceans and so are more closely related to shrimps than they are to insects. There are several hundred species of native slaters, but the most common slaters found in urban gardens are introduced from Europe. Slaters have several other common names including woodlice, pillbugs, and butcher boys.
Slaters thrive in damp conditions and are usually active at night. Slaters have become more of a pest in some gardens, especially in heavily mulched gardens, over the last decade or so. Slaters are usually scavengers that mostly feed on decaying vegetable matter, but they also feed on living plants.
African mallow (Malva parviflora) is a lovely ornamental shrub known for its delicate pink or white flowers. However, these shrubs are prone to slater infestations. Slaters, also known as woodlice or pillbugs, are small crustaceans that feed on decaying plant matter. When they invade your African mallow, they can quickly defoliate and even kill the shrub. Getting rid of these pesky pests takes diligence and consistency. But with the right techniques, you can protect your African mallows from slater damage.
Why Slaters Are Attracted to African Mallows
African mallows have a few characteristics that make them vulnerable to slaters:
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Moist environment African mallows thrive in damp conditions But moist soil also attracts slaters looking for decaying matter to eat Slaters need moisture to breathe through their shells,
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Tender foliage: The young leaves and stems of African mallows are delicate and tender. This makes them easy for slaters to chew through and consume.
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Debris accumulation African mallow shrubs have dense, low growth habits. Fallen leaves and organic debris can collect around the base of the plants This decaying matter is an ideal food source for slaters.
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Low light conditions: African mallows grow best in partial shade. But low light also creates the cool, damp environment slaters prefer.
By understanding why slaters target African mallows, we can take steps to make the shrubs less appealing to these pests.
Physical Controls for Removing Slaters
Regular monitoring and direct removal of slaters is required to protect African mallows. Here are some hands-on techniques to control slater populations:
Hand Removal
Pick slaters off plants and drop them into a bucket of soapy water to kill them. You may need to hand remove slaters daily or even multiple times a day during heavy infestations. Be sure to inspect all surfaces of leaves, stems, buds and the soil surface around the shrub.
Traps
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Create small tin can or jar traps by filling them with beer or yeast mixture. Slaters are attracted to the fermented odors. Place traps near infested plants and empty them daily.
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Lay wet cardboard or damp burlap on the soil around the shrub. Slaters will gather under these moist shelters which you can then shake out into a bucket.
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Use inverted melon or grapefruit rinds on the soil. Lift and dispose of them daily along with any slaters that have gathered underneath. The fruit peel attracts slaters seekingDecaying plant matter.
Alter Habitat
Make the area less hospitable to slaters:
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Remove plant debris and thick groundcover around African mallows. Eliminate slater food and hiding places.
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Improve drainage and reduce moisture in the soil. Allow the soil surface to dry out between waterings.
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Increase sunlight with selective pruning or moving plants to sunnier spots. Slaters avoid direct sunlight.
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Spread diatomaceous earth, crushed eggshells or wood ash around the base of plants to irritate slaters. These natural abrasives also dry out their shells.
Organic Slater Sprays and Dusts
Applying organic insecticidal sprays or dusts can help reduce slater populations on contact:
Diatomaceous Earth
This powder made from fossilized diatoms damages the waxy coating on slater shells, causing dehydration. Dust it onto dry foliage.
Neem Oil
Extracts from the neem tree have insecticidal properties. Spray a 1-2% neem oil dilution onto African mallows every 1-2 weeks.
Insecticidal Soap
Potassium salts of fatty acids disrupt cells membranes and cause insect death. Spray infested shrubs every 5-7 days.
Pyrethrins
This botanical insecticide derived from chrysanthemums is effective against slaters. Use pyrethrin sprays rotated with other treatments.
Kaolin Clay
Kaolin clay powders repel and irritate slaters. Regular applications to foliage and stems will discourage feeding and activity.
Boric Acid
This slow-acting stomach poison causes slaters to stop eating and die off. Sprinkle it carefully around infested plants.
Avoid overuse of any single organic product to prevent slaters from developing resistance. Rotate between different sprays and dusts for the best results. Always follow label directions for correct dilution rates and safe usage.
Cultural Controls and Prevention
Certain gardening practices can make the yard less welcoming to slaters over the long-term:
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Improve drainage and reduce compaction in African mallow beds.
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Allow soil to dry out partially between waterings.
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Space plants appropriately to increase air circulation.
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Clean up fallen leaves, debris and mulch regularly.
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Pull any weeds, which can provide cover and moisture for slaters.
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Apply a layer of sand or diatomaceous earth around the base of plants as a barrier.
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Introduce predators like birds, frogs, spiders and beetles to the landscape.
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Avoid excessive nitrogen fertilization, which leads to succulent growth that slaters prefer.
With vigilance and persistence, you can gain the upper hand on slaters attacking your African mallows. Be patient – it can take time to deplete large pest populations. But using a combination of physical removal, habitat modification, organic sprays and prevention will lead to success. Relax and enjoy your beautiful slater-free African mallows!
What are Slaters & How to Get Rid of Them
Slaters belong to the order Isopoda, which is part of the arthropod class Crustacea. This class mostly contains marine and freshwater aquatic animals such as shrimps, crabs and crayfish. This explains why slaters are such different looking animals to other garden invertebrates such as insects and spiders.
There are about 300 species of native slaters found in Australia and they usually occur in high rainfall areas, and are found under logs, rocks and leaf litter in bushland. Introduced species are common in urban and rural areas in the higher rainfall areas of the southern half of Australia. In gardens they are usually found under mulch or in compost bins.
In their native habitats, slaters are usually scavengers that feed on decaying organic matter. In that sense they are an important part of the decomposition cycle, meaning they help return nutrients to the soil. This explains why slaters are so common in compost bins, unfortunately pest slaters also feed on living plants.
Common pest slaters include the Garden Slater or woodlouse (Porcellio scaber) and the pillbug or butcher boy (Armadillidium vulgare).
Slaters have seven pairs of legs, two pairs of antennae (one pair is obvious, and the other pair is hidden), and eyes on each side of the head.
Adult Garden Slaters (Porcellio scaber) are grey-brown in colour, flattened, and up to 17 mm long. A pair of appendages known as uropods are usually seen extending from the rear. Garden Slaters feign death when threatened.
The Pillbug (Armadillidium vulgare) is dark grey or black, up to about 18 mm long, and has the appearance of being armour-plated. Pillbugs can roll into a tight ball for protection like an armadillo – Armadillidium literally means armadillo-like. In some countries Pillbugs are called roly- polys for obvious reasons. Pillbugs dont have visible uropods.
Juvenile slaters are initially translucent white with only 6 pairs of legs, but later in the life cycle grow the seventh pair and look like miniature adults.
Females lay eggs into a brood pouch, known as a marsupium, under their bodies. Females normally produce about 40 eggs per brood and lay 1 to 3 broods per year depending on the conditions. Eggs hatch within the marsupium and the young remain there for about 2 weeks. When the young emerge from the marsupium they pass through two moults before growing their seventh pair of legs.
The young continue to moult (and grow) every week or so for the next 4 to 5 months before reaching maturity. When slaters moult they dont shed their entire skin in one go. The rear half of the body sheds first, and the front half sheds a couple of days later. Adult slaters can live for two to five years.
What Plants are Impacted by Slaters
- Strawberry and other soft fruits (especially fruit touching the ground).
- Trailing plants such as cucumbers where the fruit is touching the ground.
- Foliage and roots of potted plants in greenhouses.
- Chunks chewed out of seedlings.
- Chunks chewed out of strawberries and cucumbers etc. at ground level.
- Missing seedlings.
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