Oct 012009
 

by Susan Taylor
Originally published in BellaOnline

In general, leaf loss in Cattleya Alliance orchids is not considered to be a major growing problem. Unless you have very good growing conditions and have solved most of your cultural problems, you are going to lose the leaves on the older pseudobulbs of your Cattleyas. It is an exceptional grower who can keep these plants happy enough to produce a specimen plant. That is not to say that the hobby grower cannot do better to reduce leaf loss than the average grower. There are three main reasons for leaf loss: diseases/insects, culture and genetics.

In the diseases and insects category, scale is the main culprits. Scale is easy to spot once you have ever seen it – a grouping of white fuzzy spots. Left untreated scale will overtake a plant and ultimately will kill it. As soon as you see evidence of these pests, remove the plant to a location away from your other plants. Manually clean up any obvious insects or spray the whole plant with Bayer’s Rose and Flower Insect Spray (dual action) which will kill any pests that it touches as well as be absorbed in the plant and will kill adults as well as any sucking insects. Continue to spray for about 3 months.

Cultural practices which will cause leaf loss include overwatering, under-watering and excess cold and or heat. Overwatering will cause the roots on your plants to die off so they cannot support the plant. In an attempt to stay alive, the plant will shed extra leaves and try to keep the new growth alive. If possible, look at the roots of your plants – some growers actually take their plants out of the pots periodically to assess the growth. An old rule of thumb says that if the second oldest pseudobulb (generally from the previous year) is wrinkled and desiccated, you are either under or overwatering. Take your plant out of the pot to see which it is. If the roots are good and plump, then you’re under-watering. If they are all dead and rotten, you have overwatered. Repot and change your culture.

Another cultural practice which will cause leaf drop is very cold temperatures in the winter and very hot temperatures in the summer. Most Cattleya Alliance plants will withstand a wide range of temperatures, but very high and low temperatures, even within their range, will cause them to be stressed and lose leaves.

Genetics will also determine whether the plant will grow large for you or lose leaves once they are a couple of years old. There is little that can be done for this aspect but to determine through trial-and-error which plants are best for your growing conditions and stick to them.

One point to keep in mind is that if you can keep from doing it, it is much better to allow the leaf to drop off naturally than to cut it off. If the leaf will not snap off with light pressure, leave it on until it is ready to come off. The plant will seal the wound through a natural drying process which will keep any pests or disease from using the area to invade the plant.

Oct 012009
 

by Susan Taylor
Originally published in BellaOnline

Repot
Fall is a good time to repot those orchids which have already bloomed and are going into a rest period or growing pseudobulbs which will mature over the winter. With cooler weather the transplanting process will be easier to bear. Some of the varieties to repot are Doritis, Doritaneopsis and Encyclia as well as Phal seedlings.

Move Your Phals to a Cool Spot at Night
Fall is the time to move your Phals to a cool spot, around 60 degrees Fahrenheit or 15 Centigrade at night, until you see inflorescences starting at the base of the plant. When the growths are about 2 inch or 5 centimeters long, the plants can be moved back to their normal warmer conditions. Stake the inflorescence beginning at about 6 inches or 15 centimeters and make sure that you keep the plant positioned the same direction in relationship to the light for best presentation of flowers.

Move Plants Inside
Prepare all your plants for moving into warmer conditions before the first cold front arrives. Check them for insects in the pots, clean up dried out sheaths where bugs might hide and even start moving some of the tender plants inside as night time temperatures cool. Then you will ready for that first really cold weather and only have a few plants to take care of at the last minute.

Water and Fertilizer Requirements Change
Fall is a time when you will need to adjustyour watering and fertilizing schedules to accommodate the variable weather conditions. As the temperatures cool your plants will use less water and start slowing on their growth, so will need less fertilizer. Generally I keep with my same fertilizing schedule of every other watering throughout the year. But in fall that watering goes from twice a week to every five days and then to once a week in winter.

Keep Your Air Circulation Going
It is especially important during the fall and winter months to keep air circulation going especially in a greenhouse or enclosed growing space. Mold, mildew and insects thrive in stagnant conditions and will cause many problems without proper air circulation.

Light Requirements are Changing
Fall brings changes in light conditions for inside and outside growers. Make sure your plants are getting enough light with the changing conditions or move them around if you are removing shading used during the hot summer months. Leaves on orchids can burn if they get too much direct sunlight.

Oct 012009
 

A couple of years ago, I asked Andy Easton why some of our Catts had black tipped leaves. He said might be a calcium deficiency. Since then I have added 5 Tums tablets to every 20 gallons of fertilize solution. I start softening the Tums several hours ahead of adding the fertilizer, 15 aspirin, and detergent to the mix. Our black tips are gone, and while the calcium is at best in suspension, the particles seem to some how get into the roots.

Dot Henley