There are some diseases and pests that can impact our plants. We can help prevent many of them with good growing practices such as using a sterile potting mix, and keeping the pots and seed trays sterile between uses when reusing pots, having good ventilation, and avoiding over watering. Keep a close eye on your plants. The more often you look them over the sooner you can catch a problem before it becomes widespread.
Also and MOST importantly ISOLATE any new plants or plant material in a place away from your collection for at least 3 to 5 months while you watch for problems.
The following are some of the more common pests and diseases....also a link to take you to the Dr. Optimara page that has information and treatments that also work on Streptocarpus.
Here is a great link as well to the Dibley Website on pests and disease.
Root Rot or Phytophthora
Over watering and or leaving the pot in standing water will cause root rot. The roots become surrounded with water that cuts out the air they need to survive and this leads to the death of the roots. Symptoms of this is wilted leaves. If you tug lightly at the plant and it comes away from it's pot in your had you have no root left and it is to late. Cut a few of the leaves off and soak them until they are turgid and get them down for babies to replace the lost plant.
There is also a root rot caused by a microscopic soil borne organism. To read about this please follow this link. Click here to read about it.
This disease appears as small white powdery patches on the leaf surfaces. It can also be found on the flowers and flower stems. It can spread rapidly. This is usually caused by poor growing conditions or large temperature swings. Ventilation will help discourage the disease. Be sure your plants aren't to closely packed in.
This shows as a gray fluffy growth on the plants. Damp and cool conditions help this gray mold to spread. Ventilation and warmer conditions help this one and always remove all diseased parts of the plant quickly.
Dibley's Book 'Streptocarpus' names two of these that I have never seen nor heard of yet.
Impatiens Necrotic Spot Virus
Symptoms are a streaking and mottling of the leaves so that the leaf appears to be random mixture of light and dark green areas. Thrip spread this disease. You can also spread this by not sterilizing cutting instruments between cuts of different leaves. Use milk to sterilize blade between cuts.
Streptocarpus Flower Break Virus
The flowers, instead of being a uniform color, will have streaks of varying shades of the color.
You will detect this by seeing them on your plants. They are soft bodied and can be found in many different colors. They feed by sucking the sap of the plants.
I have easily killed off aphids using simple liquid dish detergent and water mix sprayed on the plants each day for a week.
These live in the potting medium and feed on the roots. They are very small (1/12 of an inch) and white and can blend in well with the perlite in the mix. You can spot an infestation by pulling the root ball from the pot and looking for webbing's or a waxy buildup. Sometimes you can find them floating in water reservoirs if wicking.
Marathon or Imidacloprid works wonders on this pest.
You will find these as fluffy masses of cottony balls along the plants veins.
These are tiny black flies. They feed upon the moist organic matter. They flies in adult stage are not in themselves harmful to the plant other than the chance of spreading disease. the larvae are what cause damage to the plant by feeding on the roots while living in the potting mix. You can identify the larvae as small slender white to clear looking worms with dark eyes.
Marathon or Imidacloprid works wonders on this pest. I have also used Gnatrol with great success.
Slugs will eat the leaves and the flowers. You can identify their damage by the slimy trails that they leave.
Cyclamen or Broad Mites
These are microscopic pests and can do allot of damage before you can figure out what is going on. Infested plants will have distorted leaves that if badly infested will turn brown hairy and cork looking. The flowers will be deformed. You will need at least a 30x lens to see them. It is best to send your suspect plants in for proper ID of the pest so you are sure what you are dealing with. Just because you see a mite does not mean you have one of these "bad" mites. It could simply be a predatory mite out looking for a meal.
It is best not to mess around with any form of control other than a proven miticide that is made to kill the target mite you wish to eradicate. Some great miticides that are safe to use on streps are Avid, Pylon, Forbid and Kelthane (if still available to you). I have had none to little damage using any of these on my plants.
A small insect that is yellow and torpedo shaped. You will find them by seeing spilled pollen. If you blow or tap on the flowers you can usually see them emerge. The young feed on the plant and then drop into the soil to emerge as adults.
Click here to visit Dr. Optimara for treatments and more information about these pests and diseases.
Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the webmistress nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact your nearest Cooperative Extension Service in your county.
'Streptocarpus' by Rex Dibley as Reference.