Monday, November 29, 2010

Cycads


This article is written for those who have a problem with their cycad plant, want to avoid the common maladies of growing cycads or would like general sago palm care tips. In this article we discuss the problems that we’ve seen frequently and advise as to potential remedies that seem to help. It is meant to stimulate the reader into inspecting his plants for yellow leaves, brown tips, rot, etc., and coming up with therapeutic modalities for his plants. The better one gets at this, the better grower he will become.



What’s Wrong?

Inspect your plant

In growing cycads, it is very important to make a habit of looking at your plants. Inspection is key to good growing of cycads. They will usually demonstrate to you that they have a problem. However, it helps to know what to look for while inspecting. This can lead to your diagnosing the problem, or at least let you know something is wrong.. Once you establish what the problem is, you can set out to solve it. Described below are some of the things that you can look for while inspecting your cycads. Be aware that different climatic areas may see different problems than we've seen here in Southern California. However, most of the problems discussed below are quite universal to all growing areas. The problems of insects and pests is not dealt with here and will be discussed in a future article.


Encephalartos transvenosus, suspected of rot.



Bottom rot on Encephalartos caudex.



You see visible rot on your caudex or roots: Sometimes one might see rot on the trunk of a cycad. Or, you might see it on inspecting a caudex in pumice that you are trying to root out. Obviously, this requires you're bare-rooting the plant to inspect the roots and base of the caudex. Unfortunately, rot can hide and be deceptive, even starting in the most hidden, deepest roots. With rot, the first thing one notices is that the caudex or root tissue is soft. Rot manifests itself as a dark tan to brown/black color in the caudex or trunk . Rotting roots tend to be soft, darker colored, and lacking secondary roots coming out. This is opposed to light, fleshy healthy roots . Usually the rot involves the lower caudex in it’s subterranean area or the roots. Rot can cause cycads to decline or possibly die if it is not addressed. If you find rot on your caudex, use a sharp, sterile cutting tool (knife or saw) to remove the rot. Cut the rot away until you have only hard tissue that is whitish or light tan in color. Note: in some cases you may not find whitish or light tan tissue; in such cases, cut back to hard tissue. Be careful, if you cut the caudex too much you risk the plant dying. If the rot is on the roots, one needs to individually remove involved roots, dissecting up to clean, healthy tissue. Below are guidelines to the treatment of rot after you've dissected it away.


Encephalartos longifolius, with crown rot forming multiple heads.



Caudex rot on Encephalartos showing soft tissue.



Rooting hormone brand Take Root; a combination of root stimulant and fungicide.

General guideline in the treatment of tissue rot:

1) After you have cut away the rot (trunk or roots), soak the plant in both a fungicide and root stimulant. First soak your plant in a fungicide, like Daconil, for 30 minutes. Always follow manufacturer's instructions about usage and safety on any chemical. Next you will want to soak your plant in a root stimulant, like DipN’Grow, vitamin B1 or B complex (most liquid root stimulants will work), for 30 minutes. The reason why I recommend soaking the plants for 30 minute intervals is because it allows the caudex to absorb both the fungicide and root stimulant into its tissue
2) Sprinkle a powder root stimulant, like Take Root, onto the base of the caudex and/or the root(s).


Pure pumice.

3) You should now seal the cuts with an agricultural tar. This assists in keeping the cut surface clean and also helps to protect from future rot. Melted wax preparations can also be used.
4) We use new clean pumice (or scoria) to re-establish the plant. It is a dry medium and you are less likely to incur rot or other problems. This typically means submerging the treated area of trunk or roots directly into the pot of pumice. If pumice is not available, coarse sand can work. Use a pot that is not overly large for the caudex.
5) The time it takes to reestablish your plant can be three to six months or even longer. Failure will be evidenced by the progression of the rotting tissue and failure to establish leaves or roots. You may wish to bare root the caudex for inspection from time to time. One must repeat the cycles above if rot is rediscovered.


Caudex that hasn't done anything in a long time.

The top of your caudex is soft
This is an ominous sign. It usually means the caudex is in the process of or about to collapse and die. It is usually due to rot and the plant is usually near death. One would typically see the leaves turn brown and fall downward . They may shrivel. On grasping and pinching the crown of the caudex, it will be soft and compress inwards. It might actually collapse beneath the pressure of the fingers. This often means the demise of the entire plant. If the softness to touch is minimal, quickly treat the crown with a drenching of fungicide, and repeat on a regular basis. If the crown is collapsing, one can dissect away the crown of the caudex until healthy tissue is found. Often this is unsuccessful. The mechanics of doing this are discussed elsewhere, but one would be working from the top of the caudex downward. If one is lucky, new suckers will emerge from this dissected level and the plant will survive. More often then not, this plant is bound for the garbage can and is terminally ill.


Encephalartos, rotted and collapsed caudex.

E. transvenosus, inspecting caudex for rot and noting softness to the crown of the plant.



E. transvenosus, rotted caudex. Note it falls apart with ease. This caudex is dead.

An unrooted caudex does nothing
We’ve found that a healthy caudex can take anywhere from six months to two years to establish adequate roots for survival. Some species are faster than others. For instance, Encephalartos horridus established quite quickly while Encephalartos inopinus gets roots much more slowly. Sometimes the latter will even throw leaves prior to establishing roots. This certainly makes one apprehensive, but it is not always a fatal observation. However, sometimes months and years go by and nothing happens; no roots, no leaves. The first thing to do is to inspect the caudex. Feel it in your hands. Is it firm? Is it still heavy in the hand? Does it feel light? Firmly press the sides of the caudex. Does it collapse somewhat, especially toward the crown? When a caudex goes bad and visual inspection shows nothing, rot is often most evident near the crown of the plant or sucker. Are the cataphylls loose? Pull on them gently. Do they easily pull out? Try float testing the caudex. Unobserved central rot can make the caudex float. If everything seems OK and you find nothing, all you can do is place the sucker back in pumice and wait.
A rooting caudex throws leaves before it roots
This is always a worrisome problem. It is never the ideal scene, but sometimes happens and can still result in a healthy rooted plant. We always like to see vigorous roots before a throw of leaves. This can occur just because of the natural cycle of the offset. Let’s say it was about to throw leaves and you removed it for propagation. It will continue to leaf out regardless of being removed. Other times it happens six or twelve months after sucker removal and yet before rooting. In either case, it poses a risk to the new caudex. It is generally agreed that there is a risk of desiccation and death of the caudex as the leaves lose water and the caudex has minimal ability to absorb water without roots. Also, the leaves don’t have a nutritional flow except from the caudex. The throw of new leaves might have used up the energy reserves of the caudex.
Once observed, the problem is what to do. Remember to inspect for and treat any rot. One may treat with fungicide and certainly place the caudex back in pumice. But, what of the leaves; remove them or leave them in place? There is no perfect answer for this, but most growers would remove all or part of the leaves thrown. In actual fact, usually these leaves will abort soon after throwing and seldom do they persist as healthy leaves. Sometimes the collapse of these leaves is rapidly followed by a collapse of the caudex. Yet, if they survive, could they not be able to offer some photosynthesis and creation of energy? For this reason, some would say remove all of the leaves except a few and cut those remaining leaves in half. Once repotted back into pumice, carefully avoid watering the crown on such a plant.


Encephalartos caudex showing crown rot, evident as soft scales near the crown pull apart.


Encephalartos, healthy caudex but no roots and no leaves as of yet.



New leaves shorter than new ones.


Leaves are shorter than normal
If your leaves emerge shorter than they did the last time, there can be a few problems:

a) If you are acclimating your cycad (working it out into sun), the new leaves may be shorter than those which flushed in a shadier environment. This is not a problem; your cycad will grow out of it.
b) If this is the first throw of a recently established sucker or a recently transplanted cycad, short leaves can occur. This will change with successive throws.
c) A throw of leaves in the coldest part of the winter can stunt their length. You might see this on a recently imported and established caudex whose "biological clock" is set to another hemisphere.
c) Leaves emerging shorter can also be an indication of a cultural problem. This could be nutritional requiring treatment with fertilizer or microelements. It could be from a poor soil mix or poor soil aeration. Or, it could be a symptom of caudex or root rot. If you think it is indicated, carefully remove that plant from its pot and wash away the excess dirt with a hose. Inspect the roots or caudex for rot. With a plant in the ground, gently rock the cycad to see if it is loose in the ground, suggesting root rot. You can also check the trunk of your cycad to see if it is soft in exposed areas. If rot is found, treat as described elsewhere in this article.
Keys to good culture.

How to avoid problems

“An ounce of prevention is worth a pound of cure”. It might even be that it’s worth many pounds of cure with cycads. Below are some simple rules to follow.

Inspection

This is one of the most important things you can do. Follow the guidelines mentioned previously and practice observation, especially watching for problems or failure to thrive. Usually you can find the problem and fix it.


Growing the right cycads

Growing the right cycads for you area is important. This will involve your talking to someone or doing a little research on your own, but it can make a huge difference in your garden. You will find that some cycads want a tropical environment where some want a dry one. Fortunately for us in Southern California, we can grow most cycads. Our limitations here are with those cycads with the most tropical demands. If you live in a temperate or colder area, tropical Zamias might prove impossible without a greenhouse. You might also find that South African species of Encephalartos grow better than those from Central Africa. Also, very humid climates such as in Miami or the Tropics might find arid growers like Encephalartos horridus prone to rot. This might require special preventative cultural techniques. For the greatest chances of success, get species right for your area.

Drainage, drainage, drainage

Regardless of your soil type, always maintain good drainage. The soil should never be waterlogged. Sand, pumice and gravel help promote drainage. Very fine sand, leafy organic material and clay-type topsoil slow it down. If it is impossible to offer good drainage in the garden, mound up you cycads above the soil line so you can control the water content of the soil.


Soil

Either make or amend you soil to create good drainage. See our article on cycad soil for specific formulas. Remember that the organic components of cycad mix can break down, resulting in “muck” at the bottom of the pot or an impediment to drainage. Repotting is the remedy for this problem. This is important for container culture. In the garden consider amending with sand. If you can’t buy or obtain materials for a good cycad soil, think about using a cactus and succulent mix. These might suffice.




Adequate sun

We have seen many promising cycads stall because they have lost their sunlight. This is usually the result of competitive more rapidly growing plants. If a species wants sun, remember to maintain it. Loss of sun will lead to a plant that just sits there and doesn’t do much of anything.

Fertilizing

Fertilizing is an important part in growing any plant. The key is to know what kind, how often and how much you should fertilizer you should use. We recommend using a slow-release fertilizer like Osmocote, using an N/P/K ratio that is 3-1-2 or 3-1-3. An example of a good fertilizer might therefore be 18:6:18. You should fertilize once every three to four months, depending on your formulae and release rate. I always recommend that you use a little less fertilizer than what is suggested on the bag because you don’t kill plants with too little fertilizer, but you do with too much.

Watering

Watering is an important part of growing cycads, because there’s hardly a cycad that likes to have wet feet. Get use to inspecting your garden soil or the soil in he containers. Don’t let it stay too damp. Drying out near the surface is preferable on most species. Typically, watering frequencies for temperate weather is about once, or possibly twice a week during hot weather. During the winter, once every week or two is usually adequate. For desert type environments, adjust the frequency depending on the soil moisture content. For tropical environments, try to avoid conditions where the plant and soil are continually damp. Mounding might be necessary. Or, overhead shielding during the rainy season might be needed. Also, regardless of where you are, water the garden or container soil, not the crown of the plant. Repetitive watering of the crown will lead to rot. This means that frequent overhead sprinklers can be a problem. Ground bubblers on timers can be great for the cycad garden. This also explains why climates with daily monsoon seasons can lead to difficulties with some species.

Ventilation

In a greenhouse environment, ventilation to provide adequate air movement around your cycads will help prevent mold and rot. Stationary oscillating fans or intake/exhaust fans can help accomplish this. Poor ventilation often causes mold and scale problems in the greenhouse.

Prophylactic treatment

Get into the habit of inspecting your plants. If you see fungal problems or rot, treat it early. Fungicides can also be used prophylacticly to avoid problems if you are anticipating them. This would especially apply to plants grown in a humid greenhouse.




Oscillating large fan in the greenhouse.

In this article we have covered many of the basics in protecting your cycads. The great thing about it is that cycads really do not take much maintenance at all. You could say that they almost thrive on neglect. Just be careful when you water, don’t fertilize too much and make sure that your cycad is in a quick draining soil and has adequate light. If you do the things discussed above, you should become a successful cycad grower.

- Posted by The Zeal Group