The Yellow Farmhouse Garden

January 3, 2017

Preventing scale honeydew on overwintering plants inside your home

With Christmas and other hectic, holiday happenings , now may not seem like the best time to check those plants you brought inside for winter but it should be done soon.

When potted plants live outside during the summer, they become susceptible to infestations of all kinds of insects. Usually, if they are in reasonably good health they can tolerate a moderate insect attack. And natural predators like lady bugs and lace wings will keep the bad insect population to a minimum. But when plants are moved indoors, they loose the protection of those natural predators which can allow the insect population to grow.

Scale insects are the ones I have the most problem with. When I start to find a sticky coating, called “honeydew”, on the lower leaves, table, nearby furniture or floor, I know that the scale insects are ramping up their feeding. They can get out of hand quickly at that point and do some real damage to the plant– not to mention the mess they make. Honeydew is sometimes mistakenly called “sap” because the plant owner thinks it is the plant leaking sap all over the place. It’s not always easy to spot a scale infestation if you’ve never seen it before.

Yellow spots caused by scale feeding are one symptom to look for. The yellow spots are not always present however.

Yellow spots caused by scale feeding are one symptom to look for. The brown oval spots are the scale insect’s shell. The clear sticky substance is honeydew.

Scale feed by poking their “beak” into the the plant and feeding on the nutrients from the plant juices. Like most other animals, they excrete waste. In this case it is in the form of that sticky, syrupy  honeydew. Honeydew contains a high concentration of sugar. But how and why do scale insects produce so much sticky residue? The answer is that they pick their feeding spot very carefully. If you remember from middle school biology, plants have two basic types of tubes inside. Those that carry water from the roots up into the plant are called xylem. The other tubes that carry nutrients manufactured by the leaves to the rest of the plant are called phloem.

It is the phloem where the scale insects like to poke their beaks. If they pierced a xylem tube by mistake, all they would get is mostly water and some dissolved minerals. The phloem sap contains sugars for energy, proteins for growth and other things necessary to sustain plant and animal life.

The scale can’t use all of the sugar dissolved in the phloem juices so they excrete the excess sugar which then falls all over the immediate area. Since it is primarily sugar, it is water soluble and fairly easy to clean up with a damp cloth. Small plants can be rinsed off in the sink or bathtub.

My citrus trees are way too big to rinse off in the bathtub and too heavy for me to move to the shower. Instead I use a damp cloth — or even my bare fingers– to rub off the scale from the leaves and branches whenever I find them. I find that if I do a few leaves every day, I can usually keep up with the multiplying insect population, especially if I remember to start early. If you wait too long, it can turn into a tedious, frustrating job.

One other by-product of honeydew is sooty mold, a black, powdery mold that grows om the surface of leaves and other surfaces. All of that sugar provides food for sooty-mold fungus which will grow and leave sticky surfaces with an unsightly black film that can rub off onto clothing.

Even though you may feel overwhelmed by the holiday rush, remember your plants, they will thank you for it.

Bob

December 5, 2016

Blooming jade plant

Filed under: Houseplants,Indoor Gardening — Tags: , — bob @ 2:08 pm

One of our jade plants has started blooming this week. Anyone with a jade plant knows this is fairly uncommon. I have had a few jade plants through the years that produced flowers but not very many. So whenever it happens, I get a little excited about it.

There seems to be no way of predicting when a jade will blossom. Lots of people, horticulturists included, have their theories about it. Some folks on the internet say they have it figured out. If that were the case, we’d be seeing truckloads of jade plants in the stores blooming just in time for Mother’s Day or Valentine’s Day — pick your favorite holiday.

Jade plant flowers are white with hint of pink near the edges. They are about 3/4 inch across.

Jade plant flowers are white with hint of pink near the edges. They are about 3/4 inch across.

Flower production in plants can be a complex process. Before a plant can flower, it has to go through several steps before vegetative cells change into  reproductive cells, ie. a flower bud.

A basic principle in botany is that a plant, like most other organisms, will not reproduce until they reach maturity. One familiar example of this is an apple tree which might not bloom for six or eight or even ten years.

We forget sometimes, that our houseplants’s ancestors originally grew out in the wild with no help from people, thank you very much. Jade plants belong to the genus of plants called Crassula. Many Crassula species go through an annual a rest period in their native habitat. In their part of the world, the rains stop for a while and the Crassulas  go into a rest period. It’s critical for the Crassulas that the humidity falls to an arid, desert-like condition during this time.

Once the dry period is over, the plants resume growing and that completes one life-cycle. So, to induce flowering, it would make sense that we try to reproduce those types of conditions found in the wild.

OK, so here is my theory of the erratic flowering of jade plants. Many gardeners or houseplant fanciers love their plants and don’t want to hurt it, I don’t blame them. So they keep watering and feeding the plant all year ’round which keeps the plant in a continuous growth stage. The jades never get a chance to rest and they never get a chance to complete a full annual life cycle. This either delays maturity or fails to trigger the reproductive response.

Many factors are involved in stimulating plants to flower: fertility, moisture, intensity of sunlight, length of daylight, temperature extremes both warm and/or cold, length of time exposed to temperatures, air movement, insect damage, and others. The timing of all or any one of these factors can determine if and when a plant will bloom. Some easy-blooming plant species will bloom despite not growing in ideal conditions. Others, like jade plants I’m guessing, require a more complex sequence of events in order to produce flowers.

All that being said, I have noticed that jade plants are more likely to bloom is they are slightly pot-bound. So does this mean that the plants have been growing long enough that they’ve reached reproductive maturity? Or does crowding their roots induce flowering? Maybe sometime in the future a budding horticulturist will discover the secrete.

Bob

 

 

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