Pittosporum, also known as silver sheen, is a wonderful hedge plant with silvery green leaves. It’s a great boxwood hedge alternative and makes an excellent fence. Silver sheen is susceptible to a few problems that can cause the plant to become unhealthy and die.
Understanding Pittosporum silver sheen problems and how to avoid them will keep your plants healthy and beautiful for years to come.
Pittosporum Silver Sheen
Pittosporum is native to New Zealand. It grows well in zones 8-11, and it is seaside tolerant. It will grow in most soils, as long as they are well-draining.
It can thrive in full sun or partial shade but prefers shade on hot afternoons. The Silver Sheen will grow to 16 feet tall, and 6 to 8 feet wide. When planting, leave 12 to 15 feet of space between plants to give them room for growth.
Common Silver Sheen Problems
The most common silver sheen problems are related to over or under-watering. They include root rot – something that can affect a wide variety of plants such as Majesty Palms and calatheas – and brown leaves due to dehydration.
Pests can also affect the plant. These include Myoporum thrips, shield bugs, root-knot nematodes, and spider mites.
Root rot is one of the most common causes of death to silver sheen. It’s a result of overwatering. If the roots of the plant aren’t allowed to dry, it allows fungus or bacteria to grow.
This bacteria causes the roots to rot. Rhizoctonia fungus or Pythium are the usual culprits in the silver sheen plant.
As the roots rot, the plant can’t take in the nutrients it needs, and it begins to die. Unfortunately, root rot can quickly kill your Pittosporum.
Signs of Root Rot
Root rot will cause your pittosporum to wilt. The leaves may turn yellow or brown, usually starting with the tips. Growth will slow, and dieback can occur.
If root rot is the cause, you will notice the soil around the plant is very moist. This moisture creates the right conditions for root rot.
Treating Root Rot
Good watering practices are the cornerstone of preventing and treating root rot. We will go into watering in detail in an upcoming section. Generally, you should deep water the pittosporum once every 1 to 2 weeks during the summer months.
Be sure that the soil is well-draining, and allow the soil to dry between waterings.
Gypsum is also helpful for treating root rot. Add 1/4 to 1/2 an inch to the soil to help prevent the growth of Phytophthora root rot. This can be covered by a few inches of mulch.
Remove any dead branches from the plant. In some cases, you may need to remove the infected silver sheen to prevent the spread of root rot.
If the Pittosoporum doesn’t get enough water, this will also affect its health. Underwatering is not as big a problem as root rot and is typically easily corrected by watering more frequently.
Signs of Underwatering
The leaves will turn brown, beginning with the tips. You can distinguish between under and over watering because under watering will cause the leaves to become dry and brittle while overwatering will cause them to be droopy and wilt.
The soil is also a clue. If the soil is very dry, underwatering is likely to be the cause.
Reviving an Underwatered Pittosporum
To revive a dry pittosporum, you’ll simply need to provide more water. It is important to water deeply, and no more often than once a week. Your silver sheen should perk up quickly when watered correctly.
Watering the Pittosporum Correctly
Under or over watering your pittosporum silver sheen can cause your plant to become unhealthy or even die. It’s very important to be sure that you are watering your silver sheen correctly.
The most accurate way to water your Pittosporum is by determining the evapotranspiration rate. Give your silver sheen 50% of the water lost by evapotranspiration rate.
Your Pittosporum should be watered once a month during the fall and spring, and twice a month during the summer months.
Again, it’s very important to deep water. The water should penetrate a least 8 inches into the soil. If you don’t have a drip irrigation system, you can use a hose. Simply allow a gentle stream to flow until the ground is thoroughly soaked.
A gentle stream will penetrate the soil better than fast-moving water. It also primes the soil to accept the water, allowing it to go deeper into the soil.
Pittosporum pests can also cause damage or death to your plants. These include Myoporum thrips, shield bugs, root-knot nematodes, and spider mites.
If your Pittosporum’s leaves are curling or bumpy, Myoporum thrips might be the culprit. It typically attacks Myoporum trees but can attack pittosporum as well.
Signs of Myoporum Thrips
The pest feeds on the sap from leaves. This causes the leaves to curl and also stunts the plants’ growth. The thrips will live within the folds of the leaf.
Treating Myoporum Thrips
Insecticides are used to treat thrips. These include dinotefuran, imidacloprid, and combination products that include one of these systems plus bifenthrin, a pyrethroid insecticide with contact and residual activity.
Thiamethoxam is also effective, but it must be applied by a professional.
To prevent reinfestation, an insecticide should be applied twice each year.
Shield bugs are better known as stink bugs. When they are threatened or squished, they give off an offensive smell as a defensive mechanism.
These bugs eat the leaves and stems of the pittosporum.
Signs of Shield Bugs
Signs of a shield bug infestation include stunted plant growth, wilting, and spots or pits on the leaves. They can cause death to young plants as well.
Treating Shield Bug Infestation
There are several ways to treat shield bugs. You can control them biologically by introducing a predator insect. These include ladybugs, lacewings, and minute pirate bugs.
Kaolin clay can irritate the shield bugs, causing them to flee the plant. It causes no damage to your silver sheen.
Insecticidal soap and neem oil are effective if used early on. They are not as effective for treating a severe infestation.
Root-knot nematodes are parasitic nematodes. They can feed on many species of plants. In fact, they are responsible for 5% of global crop failures.
Signs of Root-Knot Nematodes
Root-knot nematodes create galls or knots in the root system of the silver sheen. Above ground, it typically causes stunted growth. It will also cause the leaves to droop or wilt because the roots can’t take in adequate nutrients.
Controlling Root-Knot Nematodes
Organic compounds for nematode control include geranial and Quillaja Saponaria compounds. Azadirachtin, which is extracted from neem oil, can be effective for light infestations.
Neem seed meal, crab meal, or oyster shell flour can be added to the soil. These are beneficial for the soil, and help prevent nematode infestation.
Spider mites are another pest that is attracted to the pittosporum. Unfortunately, spider mites can be difficult to get rid of once they are established.
They typically find their way onto your plants through infested plant material. They can also be blown in on the wind.
Signs of Spider Mites
Spider mites will look like small red, yellow, or black dots to the naked eye due to their small size.
You may see small yellow or white spots on the top of the silver sheen leaves. A heavy infestation will cause a yellow or bronze color in some areas of the plant.
Lastly, you will notice spider webs. These are typically woven around the leaves and stems of the pittosporum.
Treating Spider Mites
One of the simplest ways to treat spider mites is to spray the plants with a garden hose. This may dislodge the mites. Focus on the lower side of the leaves and use a strong spray.
Lacewings, gall-midges, and predatory mites are a great way to control spider mites naturally.
For chemical control, you can use miticides to control or eliminate spider mites.
Once spider mites are established, you may need to use several methods of control to eliminate them.
Final Thoughts on Pittosporum Silver Sheen
Pittosporum silver sheen is susceptible to root rot via overwatering. This is the most common cause of poor health and death for the plant. Pests, including spider mites, shield bugs, and nematodes can also cause damage to your plant.