The Most Widespread Succulent
By Dr. Bruce J. Hargreaves
from The Cactus Patch, Bakersfield Cactus & Succulent Society
Finishing Touches
by Bob Smoley
Prickly Pages, Greater Pittsburgh C&S
More Notes on Cacti, Succulents, and Temperature
by Ron Byrom
Prickly Pages, Greater Pittsburgh C&S
The Seven Quickest Ways to Kill Your Cacti and Succulents
by Lyle Moomaw
for 'Points of Interest,' Colorado C&S
Diseases, Pests, and Control
edited by Harriet Olds from Cacti and Succulents by P. Perl and The
Encyclopedia of Cacti by Cullman, Goetz and Groener
for 'Points of Interest,' Colorado C&S
Observations on Coir
by Harry Mays, Editor, Haworthiad
**************************************************
The Most Widespread Succulent
by Dr. Bruce J. Hargreaves
from The Cactus Patch (Bakersfield Cactus & Succulent Society, August 2000
The answer to last month's question as to the succulent mentioned in Thoreau's "Walden" is purslane (Portulaca oleracea). This is probably the most widespread of all succulents. Although most people consider it a weed, it is edible both raw and cooked and is sometimes deliberately cultivated. My brother Robert recently purchased a bunch at the local Marcado Latino and Dr. Peter Kortmann, a Dutch physician, proudly served us some from his garden in Malawi. I use it as food for our desert tortoise.
Although some claim has been made for its pre-Columbian presence in the New World, most botanists accept an Old World origin. W.J. Burchell, in his "Travels in the Interior of Southern Africa" (facsimile reprint 1967, C. Struik, Cape Town), describes feasting on purslane which covered Asbestos Hill in South Africa. Allen Moorehead, in his historical fiction "Cooper's Creek," describes how early British explorers in Australia fed on purslane.
Unfortunately, they didn't eat enough as they all eventually died of scurvy.
**************************************************
Finishing Touches
by Bob Smoley
Prickly Pages, Greater Pittsburgh C&S
It is surprising and at times amazing how much beauty and value ten cents worth of top- dressing can add to a plant. Believe it or not, this ten cents could even be the tie-breaker in a show plant (even though it shouldn't be).
Top-dressing a plant with a color-coordinated stone that picks up or contrasts the color of the show plant tells the viewer, who could be the judge, that the grower of this plant is putting forth an added effort in showing and displaying his or her prized specimen. As a grower, I find that an attractive top-dressing also increases the value of the plant. If two identical plants were side by side, I could easily receive an extra dollar for the plant that is attractively top-dressed. But where does one get all of these rocks and pebbles? I will try to point everyone in the right direction, and as you will see, a strange direction at times it will be.
Two of the most unlikely places to find top-dressings are your local feed store and sandblasting supply houses. Others that are more recognizable would be pet and tropical fish stores, and of course, your local garden centers and nurseries. At the feed store, you can find what is called what is called chicken grit. This is a crushed granite that is fed to chickens to harden their egg shells. It comes in two or three sizes, the smallest size working just fine to dress 2-3 inch pots for lithops. It also works well to top-dress freshly sown seed, but be sure to use only a thin layer up to an eighth inch. The larger size of grit is OK for pots up to six inches or so. Since it is granite, the rock is a grayish silver color with a bit of a sparkle to it.
Moving on to the sandblasting supply yard, we found a number of choice toppings available. Q rock, which comes in four grades, or sizes, is great for smaller pots and is inexpensive at seven to eight dollars for a hundred pound bag. Number 2 Q-rock is also great for covering newly sown seeds. Another sandblasting rock, black beauty, is a byproduct of the steel industry and is a shiny, jet black glass. Black beauty is really sharp looking when used to top-dress small pots of lithops and mimic plants, and provides a striking contrast color for echeverias and other succulents. Finally, some sandblasting supply yards sell a small graded river gravel that is about an eighth inch in diameter with nice earth-tone colors that look great on any pot.
Lets travel next to a good, nice-sized pet supply or tropical fish store. Here you can find some really fantastic looking aquarium gravels in almost any size or color. Some that are especially nice looking are the epoxy stones that have a nice, clean shine to them. You can also find crushed quartz that is very natural and clean looking. Also available is volcanic rock, which usually comes only a few sizes and in black, brown, and shades of dark red. The heavier grades are very good for pot sizes of six inches and larger.
Well, what's left for the garden center or nursery to sell? Well-stocked garden centers should stock many of the tropical fish gravels and small pea gravel. They might also have pumice, which can be used as a great soil additive for cactus and succulents and a top- dressing as well. A more recent product that is good for large pots is expanded clay, which are small pieces of clay that have been heated and popped, much like popcorn. Also available for larger pots are various grades of crushed marble.
If you want to get really exotic and a bit expensive, travel now to your local gem and mineral store. Here you might find crushed chips of amethyst, quartz, rose quartz, citrine, agate, and many others for those extra special plants on which you need to spend that dollar in the back of your wallet. Larger pieces of gems and minerals also make really nice accent pieces in mixed plantings. Try an all succulent planting of echeverias, crassulas, kalanchoes, or any other succulents in a low, natural clay bowl top-dressed with a clean, white aquarium gravel and accented with a few pieces of amethyst crystals and iron pyrite (fools gold) and you have an exquisite planting.
There are some practical reasons for top-dressing your plants. First, as a fine topping over newly-sown seed. Since seedlings should be kept moist at all times (in most cases), the top-dressing helps keep moisture in so you don't need to water as much. Best of all, the pots that have been top- dressed will show a lighter color as they dry out on the surface compared to the darker color of ones still moist, making it easy to tell when to water. In larger pots, the top-dressing helps hold down the germination of weed seed, which makes for a lot less work later.
One final comment wash the top-dressing material and let dry before use. This removes any impurities and finer dust particles that may be present. And please don't add any of that glue, cement, or whatever it is that the mass producers use to hold the top-dressing in place for shipment - its not good for the plants and is really tacky.
Happy Growing!!
**********************************************************************
More Notes on Cacti, Succulents, and Temperature
by Ron Byrom
Prickly Pages, Greater Pittsburgh C&S
As some of you know, for several years I have been fascinated with succulent plants ability to survive cold temperatures, especially their minimum survivable temperature. My interest comes from no sense of morbidity in my personality, although many plants have frozen to death at my hands. My interest comes instead from a complete lack of faith in the minimum survivable temperatures printed in most popular books on various succulent plants. I have found from experience that these published temperatures must be based on myth, conjecture, or conservative guesses. The only exception seems to be the relatively new World Encyclopedia of Cacti and Succulents by Miles Anderson.
In the past I have conducted some experiments using a large number of plants of the genus Rebutia including sulcos, as to the minimum survivable temperature and the results have been published here. In general, they found that no species of this genus was harmed by temperatures down to 20deg F., many would survive 10deg F., but none could survive 0deg. These notes, however, involve no designed experimentation and a limited number of plants and are, thus, much more anecdotal in nature. A trip to the Internet involved a search for weather records for areas of the world where plants in my collection grow in the wild. Certainly plants can survive, if only for a brief period, the record low temperature for the area in which their wild relatives grow. If they couldn't, all the wild plants would be dead. It also makes no sense to think that young plants or seedlings can not survive the same temperatures as the mature plants; they certainly do in the wild.
In Bolivia, where many of the South American cacti grow, Sucre had a record low temperature of 24deg F., Cochabamba 21deg F., and Tarija 19.3deg F. Across the border in Argentina, Salta had a record low of 21deg F. with an average of 20 days yearly, scattered over five months, on which the temperature went below
freezing. Jujuys record low was 15deg F., with an average of 19.5 days where the temperature went below freezing, also scattered over the same five months from May through September. Many of the succulent species are native to South Africa, especially the southerly Cape Province. In South Africa, the coldest temperature I could find recorded was 19deg F. from Johannesburg where it went below freezing an average of six days a year. For several years I have been hearing that Gymnocalycium bruchii was winter hardy and last year it survived in Paul Bowdens winter-hardy bed in Pittsburgh. So I got a plant from Paul and took several seedlings produced by Paul Hoffman and planted them in my winter-hardy bed last summer. As of March, they seem to all have survived.
They come from an area of Argentina that is somewhat warmer than either Salta or Jujuy. The coldest it got at my location this winter was 4.5 on 1/22/00, but the plants were covered with snow, which insulates, so the plants probably did not experience 4.5deg F.
I remember that while attending the University of Alaska, one day, the graph on the recording thermometer jumped suddenly from -50deg F. to 0deg. Any one who had been out that day knew that it wasn't 0deg F., which would have been a heat wave. When we investigated we found that the sensor had fallen into the snow. It was 50deg F. warmer a few inches under the snow. One of the ways that plants are killed by freezing temperatures is that the expanding ice crystals in the water inside the plants cells rupture the cell membrane and kill the cells. One of the ways that plants combat this is by expelling water from the cells in the fall in preparation for freezing temperatures. That's why the winter-hardy cacti look so shriveled in the winter. The plants rehydrate quite suddenly in the spring. So suddenly that I have yet been able to note the exact date from year to year.
Without that information I am just speculating but I suspect that where many winter-hardies are lost is if freezing temperatures occur after the plants have re-hydrated. Several years ago my winter-hardies came through -17deg F. apparently fine, only to be killed by a cold snap in April. This year I held by breath as this February and again in March as we twice had six consecutive days of temperatures above 60deg F. However, the plants were smart enough not to re-hydrate.
Watch your winter-hardy beds and let me know when your plants plump-up. Last summer I planted a badly scared Aloe variegata, free-root, into one of my flower beds. It is native to South Africa where the record low I found is 19deg F. It did all right through the summer and thrived in the fall. I kept close check on it as the low temperatures continued to decrease. It survived at least five nights below freezing, including one night of 22.5deg F., but 18.7deg F. on 12/1/00 turned it to mush. Once my windowsills fill up, I keep many of my South African succulents in trays on my living room floor during the winter, putting them out on nice days since they get practically no light indoors. Invariably several times each winter I either forget to bring them in or decide to risk it on a particular night. Other times the temperature goes much lower than predicted or the is a tender plant mixed in with the half-hardies.
I came home one cold night to find my prize-winning, 18 diameter Haworthia cymbiformis still on the porch. I rushed it inside and checked the thermometer. It read 21deg F. The plant was not harmed. Since then I have found that many of the species from South Africa such as Gasteria batesiana, and Adromischus cristatus, cooperi and maculatus can tolerate temperatures in the mid-twenties with no harm. Add to those Kalanchoe gastonis-bonnieri from Madagascar and Echeveria lilacina and Perle von Nurmberg from Mexico. Knowing this means a lot less trips in and out with those trays!
However, after writing this I did think that I had lost some of these plants to the cold. Upon further investigation, I concluded that they suffered from sun scorch instead. Despite the cool temperatures, the March sun has some power. Lastly, 24deg F will definitely kill your fuchsias.
***************************************************
The Seven Quickest Ways to Kill Your Cacti and Succulents
by Lyle Moomaw
for 'Points of Interest,' September 1991
Any number of books, pamphlets, flyers and newsletters are dedicated to showing you how to keep your valued plants alive and healthy. What they fail to point out is that even if you do all the right things, you can still manage to turn your botanical baby into composting material. The opposite of what keeps a plant alive is not necessarily what keeps it from becoming a memory. With this in mind, here are a few myths you should plain put out of your head.
Myth 1. DON'T ASK QUESTIONS OF OTHER PEOPLE WHO GROW THAT PLANT.
Just
because they've got gargantua in the greenhouse doesn't mean they actually KNOW anything
about growing that plant.
Myth 2. PUT YOUR PLANT ON A FIXED WATERING SCHEDULE.
Why water it when it
needs it? After all, it's going to use the same amount of water despite the monsoon last week or the
five days of 110 degree weather since you watered last.
Myth 3. ASSUME THAT THE PLANT IS HAPPY WHERE YOU FIRST PUT IT.
That cold,
gloomy corner on the north side of the basement NEEDS that agave to brighten things up, and by
golly, you can make it grow there despite what centuries of evolution have adapted that plant to do.
Myth 4. DON'T INSPECT YOUR PLANTS TOO CLOSELY.
Three months of unnoticed
mealybugs aren't really going to bother anything, are they? And my, my,-that sun scar really sets
off the green of the nonshriveled leaves, don't you agree?
Myth 5. NEVER BUY LITERATURE ON THE PLANTS YOU GROW.
These things are written
by eggheads for eggheads. Besides, you should enjoy the challenge of keeping your plants alive.
Myth 6. USE WHATEVER SOIL IS AVAILABLE FOR TRANSPLANTING.
If I dump enough
fertilizer into that peat muck, Mr. Opuntia will be just fine.
Myth 7. TREAT ALL OF YOUR PLANTS ALIKE.
They're all green, right? And they've all got
leaves, sort of. Hey, the plant has grown hard all of its life and now it's time to relax and get the
African violet treatment.
Obviously this isn't everything bad that you can do to your plants, but it's a good start. If you can avoid killing your plants quickly, you can usually correct whatever may be killing them slowly. But, when all else fails, call another CCSS member and commiserate together. I'll bet they know someone who killed a plant just like yours.
Lyle Moomaw, former CCSS member
*****************************************************
Diseases, Pests, and Control
edited by Harriet Olds from Cacti and Succulents by P. Perl and The
Encyclopedia of Cacti by Cullman, Goetz and Groener
for 'Points of Interest,' Colorado C&S
Diseases and pest infestation of cultivated plants are frequently the consequences of unfavorable growing conditions. Plants weakened by temperatures running too high, lack of fresh air, poor light, and excessive amounts of nitrogen are particularly susceptible to disease.
Nonparasitic diseases are always due to errors in cultivation. In spite of all of the efforts to create good conditions for growth, diseases and pest attacks cannot be eliminated completely. Sometimes they are brought in from outside or transmitted by other external influences from adjacent areas. The symptoms are frequently very serious, threatening the existence of the plant, so the use of highly efficient pest-control agents is unavoidable.
The following important points apply to every pest-control measure:
-- Use a suitable preparation that is tolerated by the species of plant in question
-- Time applications correctly
-- Comply with directions for use
-- Apply the correct amount
-- Allow for temperature variations
The basic rule is: Prevention is better than cure. Treatment must therefore always be commenced in good time. Once pest-control measures are begun, they should, as a rule, be repeated several times within a few days, since often only the larval stages, and not the eggs, are treated (e.g., red spider mite, white fly).
To prevent possible resistance to certain agents, vary the preparations or active ingredients used to control the pests. Pest-control chemicals should always be applied conscientiously, to protect one's health, prevent damage to the plants, and minimize environmental pollution. When applying a chemical in a water solution, be sure the water itself is not cold. Chemical solutions should be applied on a warm day but not in full sun, and don't apply them to dry root balls.
Appropriate cultivation practices are your first line of defense against disease and pest attack. Grow cacti and succulents to be as healthy and resistant as possible with plenty of light, fresh air, balanced feedings, and pronounced temperature differential to harden them off. They need to be checked thoroughly at regular intervals for disease and pests. Pay particular attention to any plants that haven't shown new growth and don't produce new spines in the growth period, that have unexpectedly refused to flower, that are not healthy and fresh in body color and appearance, and that are still not firm and secure in their pot even after a fairly long period of growth. Newly acquired plants should not be placed with the rest of the collection until they have been thoroughly examined, appropriately treated, and kept in quarantine. Don't throw diseased plants on the compost heap or in a corner of the potting bench, where they could become a breeding ground for generations of pests and dangerous fungus spores. Cleanliness should prevail in the cultivation premises. Always wash yourself carefully after using plant chemicals and clean all the equipment you have used.
In the following list, the most disastrous diseases and pests and the damage they cause will be described, and possible methods of treatment will be given.
Fungal diseases
Rhizoctonia rot in seedlings and cuttings causes plants to turn transparent in appearance. The wet rot proceeds from the stem base of the plant and is recognized further by its fine web of thin white/gray threads spun over the soil.
Control: Captan 50, Orthocid 50 (each 0.1?0.2%); Chinosol (0.05%); Benomyl (0.05%). In the case of sensitive seedlings, the plant compatibility is sometimes unsatisfactory. The consequence can be: reduced or retarded germination and inhibited growth. Plants affected by this fungus should be carefully removed and less-severely-attacked seedlings should be pricked out into a disinfected (preferably steam-treated substrate.
Helminthosportium stem rot is shown by the mummy-like shrinkage of young plants. This disease is brought in with seeds from the native countries of the cacti. The infestation spreads very rapidly and can cause the total loss of a whole sowing within a few days. The disease occurs only at low temperatures in combination with high atmospheric humidity. The fungus is easily recognizable by the velvety-green spore coating.
Control: The plants affected should be removed immediately and healthy seedlings transplanted. Spray at ten-day intervals with Orthocid 50 (0.2%) or Pormasol forte (0.2%). The most important preventative measure is disinfecting the seed.
Epiphyllum mosaic disease is common among cacti. The symptoms are pale yellow, slightly sunken spots that are not clearly defined and appear predominately on the edges of parts of the plant and spread toward the center. Diseased plants are very reluctant to flower. Schlumbergera, Zygocactus, and Rhipsalidopsis are easily attacked. Diseased specimens should be destroyed. Fusarium rot and wilt is especially common in tree cacti but it also effects columnar and globular cacti. This fungus frequently attacks at the neck of the root. The tissue there turns brown and sinks in. The fungus then proceeds from the roots via the vascular system to the tips of the shoots, causing wilting. If a shoot is cut open, the typical characteristic of the disease can be seen-a red- brown coloration of the vascular bundles. Affected roots are destroyed completely so that only the fibrous vascular cords remain. The affected parts that are above ground are very soon coated with reddish, salmon-colored or violet spores. The infection mostly occurs at points of injury, often due to insects having bitten or eaten a part of the plant.
Control: Use only steam treated soil; remove any plants suspected of infestation; prevent injuries of any sort; keep temperature and humidity as low as possible; avoid excess application of nitrogen fertilizers. Chemical control with Do Pont Benomyl (0.05%), applied by watering or spraying.
Pythium and Phytophthora cactorum are wet-rot pathogens that come from contaminated soil and usually attack the stem base. The damaged plant becomes pulpy and its tissue rots.
Control: Disinfect soil; destroy affected plants and their pots. Water with Prothiocarb-Previcur (0.15%) or with Fenamisul-Bayer ( 0.03%). Successes are also achieved with systemic soil treatment, using Dexon, which can be sprinkled or watered on. Moisture promotes the spread of the stem-based rot; therefore-in cool weather at least-watering should be restricted to the minimum requirement.
Anthracnose disease symptoms are circular, sunken, pale, or brownish spots, where the plant tissue dries up and becomes hard and bark-like.
Control: In the initial stage, the diseased parts can be cut back to healthy tissue using a knife that is repeatedly disinfected by passing it through a flame or dipping it in medicinal alcohol. Chemical control by spraying with Saprol (0.15%), Maneb powder spray (0.2%), Dithane, or Orthocid 50.
Black Spot, a horrible fungal disease, predominantly occurs when the humidity is too high during the cool seasons of the year.
Control: Do not subject plants needing warmth to temperatures that are too low; reduce humidity. Chemical control with Benlate, and Orthocid 50, and Captan combined with Benlate is effective as well.
Treatment of most fungus attacks calls for the affected plants and all the soil in the pot to be destroyed. Thoroughly examine plants that appear to be healthy, and wash all of the soil out of the roots. The next stage is to make up a fungicidal solution and submerge the entire plant in it for half an hour (A combination of Previcur 0.15% and DuPont Benomyl 0.05% is effective against many species of harmful fungi.). After soaking the plants, they must be allowed to dry out for five to ten days, and then they should be planted in very permeable soil (with a high proportion of pumice or lava-rock gravel, perlite, and similar substances). If one of the salvaged plants again shows signs of fungus attack the plant will need to be soaked in a mixture of Previcur and Benomyl several times at fourteen-day intervals. Hardened plants that have been correctly cultivated have a high resistance to fungus attacks.
Viruses
Viruses and mycroplasms are minute pathogenic organisms that cause a variety of symptoms in plants. Plants with virus infections cannot be cured, not even can parts of the plant be rescued. Chemical control is not yet possible. The disease is transmitted in the sap of affected plants by insects that pierce the plant body or from a grafting knife that has not been disinfected. Stunted growth and the pathological, super-abundant shoot growth of Opuntia monstrosa and monstrous- dwarf forms of some other opuntias are the symptoms of a developmental disorder caused by viruses. These strange and unique forms are consciously propagated and kept in plant collections. Insect pests
Eelworm or nematode are considered extremely dangerous and difficult-to-control insect pests for cacti and numerous other succulents. Of the latter, crassula and geranium can be very severely attacked. There are three subgroups of eelworm:
1. Root-knot eelworm. The larvae, which are about 0.5 mm long, bore into the roots, damage the plant by sucking the sap, and cause knot-like swellings due to secretions from their saliva glands; the swellings quite frequently reach the size of anything from a walnut to a fist.
2. Cyst-forming eelworm. These pests live in the roots. They burst the root epidermis, and then the females cling to the outside of the roots as brown, lemon-shaped cysts.
3. Free-living nematode. These eelworm do not settle in particular places but migrate from plant to plant by their own movement, or they can be are carried by water. A single contaminated plant can quickly infest an entire collection. Nematode are about 1 mm long, colorless, and worm-like in shape. An eelworm attack is often not noticed until the plant begins to look stunted from considerable damage to the roots. Eelworm multiply rapidly, and their larvae can become dormant for months or even years, if their living conditions are unfavorable. These persistent pests may also be spread by careless handling of infected plants, pots, and boxes; by contaminated soil, greenhouse staging, and tools; or even by the soles of shoes.
Control: Extremely careful hygiene is required to check a plague of nematode. The simplest method of disinfection is to scald the plant containers, greenhouse benches, and tools with boiling water, but not all plastic pots and boxes will survive this treatment. Chemical decontamination of these objects can be performed with Formalin or Nemafos.The soil may be decontaminated by heating (steaming) or with Basamid. Nemafos emulsion can be used to water growing plant stock, but unfortunately, this preparation is not universally tolerated by epiphyllum and other epiphytic cacti. In combating Nematode, all the mechanical and nondangerous methods should be tried first. For example, it is best to remove all severely affected roots when transplanting. Sometimes there is no choice but to cut off all of the roots and root the plant anew in fresh substrate. This can be done without difficulty with species of echeveria, crassula, kalanchoe, and sedum. Eelworm are sensitive to heat and can be killed by giving the plant a 30-minute bath in water at a temperature of 45?50 degrees C. The cactus roots should be able to stand this temperature. This kind of treatment, however, is also considered risky by some growers.
Spider mites are minute brownish-red mites hardly visible to the naked eye. They cover the affected plant parts with a fine white web. Spider mites often occur in vast numbers. They multiply rapidly in dry air and warmth and cause damage by piercing the epidermis and sucking the sap. The characteristic signs of attack soon appear as brown, grey, rusty and sometimes scabby areas of tissue which can spread over the whole plant. The attack begins in the region of the apex on globular cacti. The cacti most at risk are rebutias, lobivias, various mammillarias, aporocacti, and Chamaecereus silvestrii; the succulents at risk are crassula and faucaria. Once the epidermis has been destroyed by an attack of spider mite, it never regrows. It is a long time before affected areas are at least partially covered by new growth.
Control: Growers who cultivate their cacti hard and who find large numbers of real spiders of all sizes in their collections only rarely suffer from a spider-mite attack. This biological balance can be preserved when red spider mite gets out of control by using Tedion V18 (0.02%) or Shell-Torque (0.05%). Neither of these preparations kills the winter eggs of the mite, but they both eliminate the larvae and mobile stages while sparing useful insects and the mite's natural enemies. Mite-killing preparations (acaricides) such as Dimethoate emulsion, E 605 forte, Kelthane, or Malathion are effective. To prevent the development of resistance to certain active agents, apply these preparations alternately. The treatment should be repeated two or three times at intervals of eight to ten days.
Scale Insects occurring on cacti and other succulents are predominantly in the form of mealybugs. Scale insects occur on agaves, leaf cacti, pereskias, and some other genera. Most species of scale insects reproduce by means of eggs, some are viviparous. The flat hemispherical armor of the disc- scale insect consists of wax-like integument or hardened back skin. In the juvenile stage, the insects are mobile and have legs, feelers, and eyes. The males have wings. Females shed their skin many times before eventually losing nearly all their organs, becoming immobile, and settling in one place. Their protective shells are then firmly fixed to the host plant. After depositing eggs, the female dies and several hundred eggs begin their rapid development, protected by the shell left behind. A frequent attendant symptom of scale-insect attack is the formation of sticky honeydew, followed by the growth of sooty mold.
Mealybugs exude a white waxy substance that envelopes their entire pink-colored bodies. Unlike the armored-scale insects, mealybugs remain mobile throughout their lives. They also multiply rapidly. Their sap-sucking activity weakens and eventually kills severely infected plants. If not controlled, mealy bugs will very soon form large colonies in protected corners of cluster-forming cacti like rebutia, mammillaria, dolichothele, and echinocereus. They will thrive in the axils where they are particularly indistinguishable from the axil hairs of some species like mammillaria. They will also locate themselves at the apex or on the stem base of species like echevera, crassula, faucaria, pleiospilos and other succulents.
Control: Cacti should be continually inspected for signs of this pest's attack. Upon inspection, if only a few mealybugs are found, it is sufficient to dab them directly with an ethyl alcohol solution on a brush or cotton swab. Another method is to spray them off with a jet of water using a fine spray nozzle. The use of chemical control methods is unavoidable in an advanced stage of infestation. Use a preparation specifically for scale insects or mealybugs (Malathion 0.1%, Metasystox, Dimethoate, Basudin liquid, or Roxion) because these insecticides adhere more readily to the water-repellent wax secretions. If you use a spray, thoroughly spray concealed places on the plant. The treatment must be repeated several times at weekly intervals.
Root mealybugs are among the worst pests of cacti and other succulents. They live almost exclusively on roots and the parts of the stem that are below the surface. They are similar to mealybugs in that they also secrete whitish, woolly, or powdery wax. Root mealybugs prefer dry substrates. They multiply particularly rapidly during the dry winter dormancy period. Affected plants look pale, become sickly, and gradually die. Plants damaged and weakened by root mealybugs are especially susceptible to fungal diseases.
Control: Brush off the bugs with a stiff brush when transplanting. Dip the roots in insecticide, and transplant into new soil. Water in the spring and autumn with suitable chemical solutions like Diazion 25, Metasystox R 0.1%, or E 605 forte 0.35%. It is advisable to leave the pots up to their rims in the solution for several minutes to ensure that the they soak up the liquid thoroughly from the bottom. If this is not possible, thoroughly drench the potted plant so that the liquid runs out the drain hole of the pot. Repeat the treatment several times at intervals of two weeks.
Aphids occur frequently on the flower buds of epiphyllum and yucca, and on the plant bodies of pereskia, senecio, and other genera.
Control: Slightly toxic insecticides are effective. Care should be taken not to spray insecticide into the open flower of epiphyllum, since this will ruin it.
The white fly or scale moth attacks leaf-bearing plants almost exclusively; e.g., pelargonium, Pereskia Fouquieria, crassula and senecio. This is a pest that occurs in great numbers and is difficult to control.
Control: Special preparations must be applied at intervals of three to four days. Actellic, Alphos mister, Ambush, Dichlorvos, and Parathion have proved successful. Use preparations in alteration. White fly settles on weeds such as chickweed, stinging nettle, frenchweed, greater celandine, and others, then moves on to cultivated plants. The control of weeds in surrounding areas is therefore an important preventative measure.
Fungus gnats are black insects 3?5 mm long, that lay their eggs in humus or decaying organic matter. Their larvae cause damage by eating seedlings, tender young plants, and young roots. Places where they have fed provide a foothold for Fusarium rot. The larvae are 6?7 mm long with translucent, glassy white bodies and black heads.
Control: A preventative measure is to use inorganic sowing medium. Otherwise, many insecticides are effective but should be used with caution due to the sensitivity of tender, young plants. Take care that preparations can be tolerated by the plants for which they are intended.
Excerpts taken from Cacti and Succulents by P. Perl, published in the June 1990 "Points of Interest" and from The Encyclopedia of Cacti by Cullman, Goetz and Groener, 1986, English edition.
*************************************************************
Observations on Coir
by Harry Mays
Editor, Haworthiad
Woodsleigh, Moss Lane, St Michaels on Wyre, Preston, PR3 0TY, UK
E-mail: HMays@onyxnet.co.uk
Coir is the residue of the coconut husk after the fibres have been removed for use in the rope, matting etc industry. I have used it for my cacti and other succulent plant compost for seven years and with good results. My coir mix is used for seed sowing, growing-on seedlings, vegetative propagation and adult plants. The only alteration I make to it is the addition of more grit for plants which I know to be susceptible to rot.
Seed germinates well and seedlings quickly develop strong root systems. The stable and open structure of coir promotes rooting and root development and, therefore, the survival of seedlings. If a seedling can rapidly develop an extensive root system, it is less prone to drying out. As the compost dries out from the top, the seedling has access to moisture (and nutrients) lower down. Cuttings root well and also develop strong root systems. Adult plants in peat can be transferred to larger pots containing coir without any problems. When plants are suffering from not being repotted, a condition revealed by roots winding round and round and disappearing back into the root ball, roots should be gently prised out so that they head towards the new compost. The roots of repotted plants soon invade the coir.
For propagating plants by division, I use the compost moist. Individual plants are potted immediately; any cut surface is left exposed so that it can dry out before it is covered with compost a few days later. The moist compost helps to ensure the roots do not dry out and die back. Some aloes, astrolobas, gasterias, haworthias and bulbines can be propagated by division. Such plants will normally have some roots. If they do not, I treat them as cuttings.
Many aloes, astrolobas, bulbines, gasterias and haworthias can be propagated by cuttings. Stems are cut just below a node, the point where the leaf joins the stem. For some plants e.g. Aloe arborescens, where there is a visible internode (distance between two nodes) it is not difficult to decide where to cut, but many plants have tightly packed rosettes of leaves with no visible internodes. An injudicious cut can result in nothing more than a bunch of loose leaves. Offsets attached directly to the main stem should not be cut from the main stem until they have attained a good size by which time they should have a stem several millimetres long. This should be cut at the point of attachment to the main stem. Cutting the main stem of a compact rosette to obtain a stem cutting is probably inadvisable (but the growing point can be cut out to promote the production of offsets and some of the leaves used as leaf cuttings). If the main/only rosette is rotting from the base it should be cut back piece by piece to sound tissue and treated as a cutting. Cuttings are placed in a warm, shady place for a few days to allow the cut surfaces to dry prior to potting. For cuttings, I use the compost dry. Cuttings, which have a stem, have the stem inserted into the compost; those which have tightly packed rosettes of leaves with little or no visible stem are sat on top of the compost. The plants are sprayed daily in summer but not watered for several weeks so as to avoid any rot setting in.
It is important to recognise that changing to a new ingredient for a compost usually necessitates changes elsewhere. Because coir absorbs water so readily, less water runs to waste at each application than with peat, consequently less water needs to be applied to coir at each watering. Coir also holds more water than peat, consequently coir compost can be watered a little less frequently than peat and the proportion of other materials, which do not hold water can be increased.
Coir has a stable, open structure which is conducive to good root development. Because it allows the compost to breathe, which is essential for root development, oxygen is readily available to the roots. Coir's ability to breathe can be seriously reduce if you add unsuitable ingredients to it. Fine, silty, river sand and similar products are quite unsuitable as they clog up the compost and deprive it of air. The addition of a large grain, coarse sand or better still sharp grit is much more suitable as it helps to keep the coir open. Beware too of adding an ingredient which itself holds water. A 60/40 coir/perl mix would hold far to much water except in the hottest climate.
I have settled on using coir bricks as this is the cheapest way of buying coir in the UK, particularly when large quantities are used, and they have proved to be satisfactory. The ratio of the ingredients is 5:4:1, coir:grit:Silvaperl. To each imperial gallon of compost I add one level dessert spoon of Phostrogen ( low nitrogen P:N:K fertiliser), a level teaspoon of trace elements and a level table spoon of lime. I add Chempak 12.5:25:25 (N:P:K) or occasionally 20:20:20 as I think necessary, once a month to the water from April to September for all rooted plants and seedlings. Because of space considerations, I am still reluctant to repot larger plants with any frequency. Some plants have now been in coir for six years. The plants show no signs of deterioration and the compost seems to deteriorate less than the peat did.
About four years ago I came across bales of coir which I thought might be more economical. The coir is compressed into bales in the same way as peat, but whereas peat is moist, the coir is dry. Unlike peat, coir takes up water readily. Notwithstanding that the supplier could not provide a chemical analysis for it, I bought a bale and used it in my normal mix. The results were not as good as with the coir bricks. Plants just did not grow as quickly and I seemed to have more plants rotting though the number was not excessive. The texture of the baled coir was different; it had many fibres suggesting that it was not so well graded and processed. I wrote to the manufacturer for a chemical analysis but received no reply. A second letter brought forth a telephone call demanding to know why I wanted the information. I was eventually informed that they did not commission chemical analyses because they were expensive! The response to my question, "How do you know the product is suitable for horticultural purposes if you do not have an analysis?" was met with the assertion it was suitable. The conversation ended with my being told that I would be sent something. I never did receive anything and I have not used the baled coir again.
Coir is an excellent ingredient for composts for succulent plants, provided it has been processed for horticultural purposes. Some coir contains excessive salt which is detrimental to plants. Reliable distributors of coir for horticultural purposes will buy from a source where the salt content is lower and will also remove any excess salt if necessary. Coir is also deficient in nutrients, consequently these must be added as indicated above. In the UK some coir bricks are sold with added fertiliser, ready for use, but I find it is cheaper to add my own. A reliable distributor will be able to supply a chemical analysis of both his coir and coir with added fertiliser.
In succulent plant circles we hear a lot about the necessity to promote the conservation of succulent plants and their habitats, but a lot less about the need to ensure that our activities do not adversely affect the conservation of non-succulent habitats, which are perhaps far removed from our minds. If we use peat we are actively engaging in the destruction of peat bogs and the flora and fauna they support. If we do not we are helping to conserving peat bogs. Coir is a bye product of the coconut industry and it is renewed every year. Coir is used in composts because it is a very suitable ingredient, but a by product of its use is the conservation of peat bogs.