Steve Howard’s October Australian Epiphytes and Terrestrials Orchids Cultural Notes for Adelaide’s conditions.
October sees many native epiphytes finish flowering and shortly it will be the best time for potting on and division as new growths are due shortly. The earlier you start, the more time the orchid has a chance to initiate new growth and mature it in time for next years flowering.
Remove spent flowers as leaving them on the plant in wet and humid conditions leads to rot caused by botryitis.
Be aware that aphids are in big numbers now and will cause grief to flowers and new growths.
Malathion at 1 ml/ litre of water will knock them out.
Repeat fortnightly for 6 weeks to break the breeding cycle.
Apply lime to plants grown in bark to counteract acidity.
Most terrestrials nearing completion of the season.
Start drying off once leaves start yellowing. Keep water up to those staying green.
Additional shade helps now as suns intensity increases
Steve Howard’s September Australian Epiphytes and Terrestrials Orchids Cultural Notes for Adelaide’s conditions.
Mounts daily. Generally moistening roots only.
Pots weekly. Small pots twice weekly depending on weather.
Pots can dry out faster on warmer days so keep a watch on conditions. Note some terrestrials will commence summer dormancy towards the end of the month. Those that do show signs can have water reduced somewhat.
Weak organics like Seasol and Powerfeed applied in low doses can benefit colony type greenhoods.
Low nitrogen always best for native epiphytes. Top up epiphyte pots with dolomite lime and a dash of blood and bone. Seasol a useful additive now as new seasons root start.
Pests and Disease
Botrytis will rot new buds in cold damp weather as fast as it attacks new growths from now. Aphids will increase sharply this month and favour new growth and spikes. Pyrethrum sprays eco friendly and work well, so does a hose but dry spike straight after.
Some terrestrials will rot this month if conditions have been too wet or stagnant over winter. Note this for next season and add more drainage if this has been an issue.
Keep flowering plants under cover to enjoy as can be rather wet and cold as well sunny and warm this month. Start repotting and division once flowering finished to give plants longest possible time to establish over new growing season.
Time to get busy and take note of the jobs of potting and division to be done. Sept and October are the best months to work on the collection before the hot weather sets in.
Do you have small slugs and snails in your pots? Get a cheap coffee grinder and grind up your snail pellets. Sprinkle in the pot and water them in. Bite size for micro slugs and the baits get right into where they hide.
[Terrestrials are not repotted until summer – Steve will have more on that later]
There is a lot of information on the web about treating scale, some relevant to a specific country, some accurate, some not and much that is contradictory.
The following information is based upon treatment methods that the Native Orchid Society of South Australia (NOSSA) growers have found most effective.
WHAT IS SCALE?
Scale are tiny sap sucking insects of which there are several species in Australia. The female adults build a shield-like cover for protection. The shields are often brown but can be white or red. The shield can be up to 3mm in size. Once a shield is built the adult does not move about but stays in the one position. Ants farm scale as they exude a honeydew sap, a food source for the ants.
Immature scale or crawlers do move about. These can be a different colour from the adult eg juvenile brown scale can be yellow, other species can have grey juveniles. They are lightweight no more than 1mm and easily windborne.
The life cycle is short, and for many species, within a month there is a new generation of scale. Scale multiply rapidly.
Scale tend to attack epiphytic orchids. Evergreen terrestrial orchids may be affected but not the deciduous ones.
EFFECTS OF NOT TREATING SCALE:
Apart from making the plants look ugly, scale left unchecked can
Quarantine and treat new plants before introducing them to the orchid collection
newly acquired plant can be a major source of scale infestation
for thoroughness, use both a contact and systemic spray (see below Types of Sprays)
schedule spraying 2 – 4 times a year
Consider relocating ferns if they are under orchid benches as this can often be a host for brown scale.
If free-standing bench or hanging pots are free of scale and plants are not touching any other surface than applying Vaseline around each of the feet/lower part of the hooks will prevent ants and crawlers from moving into the area.
Vaseline is waterproof and so will be effective for a long time.
Biological control alone appears to be ineffective but the following is a list of known predators
Crypotlaemus montrouzieri Native ladybird feed on mealybugs and felt scale
Mallada signata, Green Lace Wings, feed on aphids, spider mites, various scales, mealybugs, moth eggs and small caterpillars
Aphystis wasp species
Scale are hard to eliminate entirely. Vigilance and persistence are important factors in controlling scale.
Treatment works either by
a direct contact spray whereby the insect is suffocated by smothering. This is effective for all stages of the life cycle but particularly for the adult under its shield.
an application of a systemic chemical.
or a combination of both.
For treatment to be effective the leaves (both upper and underside), crevices, sheaths, pseudobulbs, stems must be thoroughly drenched with the spray of choice.
Types of Sprays
Whatever type of contact spray used, treat every 2 weeks for three treatments
Soapy Water (for those who like using home-made remedies)
Using pure soap (not detergent), suds up a bar in a bowl of water, and pour into a spray bottle.
This week we continue with both Part Two and Part Three of Brendan Killen’s Rescuing Apparently ‘Dead’ Orchids which appeared in the Volume 31 No 9 October 2007 and Volume 31 Bi 11 December 2007, respectively.
Rescuing apparently ‘dead’ orchids. Part 2 By Brendan Killen
PLANT #2 – Dendrobium Alick Dockrill “Pale Face”
The cane pieces of this plant were inserted into a bark mix at the same time as the canes of Den. Jayden ‘JANE’ [See the July Journal] were inserted into sphagnum moss. The outcome is three healthy growths.
Note the dried ends of the canes where they were cut into separate pieces. As you can see from the photograph, I used a green twisty to hold the canes in the bark as a fairly solid bunch – I find this is the best way to keep the canes still whilst they are developing sensitive new growths. I have found that no matter how bunched-up the canes are, the new growths always find a way to the surface.
Here is a different angle on the new growths with my fingers providing some perspective on the size of the growths.
Note that they are significantly larger that those on the Den Jayden ‘JANE’, with the same time in the pots.
I do not consider this evidence of the worth of bark compared to sphagnum moss.
I find that different hybrids and species behave quite differently in terms of their speed and timing of production of new growths. I believe that it is a function of what species are in the background of these plants and the time of year the rescue is undertaken.
Here is the same plant 5 weeks later. The new roots are protruding from the pot and the new growths are extending themselves – all of this at a time where severe water restrictions limit me to two waterings each week by watering can!
A further 4 weeks of cultivation and bright, warm weather has fully extended and hardened the new growths.
The larger growth should produce a flower spike this Spring.
This is a plant that the late John Purvis gave me just before he passed away. Because it is a special plant to me, I cut an old cane into three pieces to produce a back-up plant, just in case my piece of the original fell foul of the orchid gremlins.
As you can see, it is the least developed of the three plants featured in this article. And yet, the parent plant has produced two magnificent new growths in the same period. I feel that the 12.5% of Den. bigibbum and 12.5% of the hot growing Den. tetragonum var. giganteum have influenced this. This new growth has probably been encouraged since the relocation from Adelaide to Brisbane where the temperature differences overnight are more subtle than in the Adelaide Hills where the plants were previously cultivated. The two hot growing species in the plant’s background were probably held back by Adelaide’s much cooler overnight temperatures. Anyway, this is purely conjecture on my behalf. What is important is that I now have a developing back-up plant for one that I treasure dearly.
Dendrobium Sarah Jane ‘Purvis’ (Photographer Josh Bridge)
The thrust of what I have written is simple – don’t give up on treasured plants that look like they have expired, because there is always hope so long as the canes haven’t turned into fermented mush! The technique is as simple as cutting canes into lengths where you have at least three, preferably four, segments from which new growths will materialise. Use sterilized cutting tools to avoid contamination of the canes. Once the new growths have emerged, give them time to produce healthy root systems and let the new canes harden before potting-on. The best time I have found to pot-on the new growths is early autumn.
Thank you to Josh Bridge for supplying images of the flowers of Dendrobium Alick Dockrill “Pale Face” and Dendrobium Sarah Jane ‘Purvis’ as they were not in the original articles.
Another technique demonstrated by John Gay at one of the NOSSA meetings a couple of years ago was to take the apparently dead canes of an epiphytic orchid and seal them in a plastic bag with a small piece of damp sponge (or other cloth) and leave them in the shadehouse. Do not let the sponge dry out. So long as there was a bit of moisture, there was a chance for new growth on the shrivelled canes. Once the growth was obvious, pot on as normal.
The following is part of a three part series on reviving apparently dead epiphytic orchids from Volume 31 No6 July 2007
Rescuing Apparently ‘dead’ Orchids
By Brendan Killen
In late Spring 2006, I had an ‘open shade house’ event at my place in Belair, South Australia. As part of the programme, I demonstrated how I rescue orchids that have all but died. My demonstration was based on many years of experience in not giving in to the demons that cause orchids to expire.
I used two orchids that everyone attending agreed would normally be tossed into the rubbish bin or compost – all bare canes; heavily shrivelled; all new growth ‘eyes’ at the base of the canes chewed out by insects. In other words, an apparently hopeless situation. I’ve never given up on these terminal plants, believing that they still had life in the old canes along as they hadn’t turned to fermented mush.
I also used an apparently ‘dead’ cane from a treasured orchid that I was hoping would eventually produce a back-up plant using the method I describe in the following text.
In one case (Dendrobium Jayden), I cut the canes into a number of segments and stuck them into a pot with heavily compressed sphagnum moss, topped with river gravel to suppress the moss from growing and overtaking the pot. In the other two cases (Den. Alick Dockrill & Den. Sarah Jane), I cut the canes into segments and placed them in a pot of small composted bark.
The following photographs were taken about 3 months after the repotting demonstration and after the plants were relocated to Brisbane. They demonstrate the benefit of the right technique and a ‘don’t give up’ attitude. This technique has not failed me yet, allowing me to rescue many prized plants that have gone on to be show-bench winners.
PLANT #1 – Dendrobium Jayden “Jane”.
This photo illustrates the emerging new growth on a Den. Jayden “Jane”. This is the first evidence that success is at hand. It is also the first new growth discovered on this plant before I inspect the canes further to see if there are any other new growths buried within the sphagnum moss.
In this photo, you can see that the new growth is very pale from having emerged from deep in the sphagnum moss with little exposure to light. The juvenile roots can be seen emerging on the right hand side.
A closer inspection reveals another growth, on the other side. Note that both growths are not coming from the ‘eyes’ at the bottom of the canes – simply because they were cut off at potting time. They are emerging from the section that joins the cane segments.
Teasing away the sphagnum moss reveals even more of the young roots. Note how the new growths are lacking any colour substance at this stage.
If I were to ignore this plant for much longer, the new growths would have rotted in the very moist sphagnum moss, neutralising my efforts. So, the lesson here is to ensure that you monitor the plants for new growths and ensure that you elevate the new growths above the sphagnum moss to give them a chance to ‘harden off’ from their immersion deeper in the sphagnum.
This photo illustrates how I have re-seated the canes within the sphagnum moss, but much higher so that only the roots are exposed to the heavy moisture content of the moss. I choose to do this instead of placing them straight into a bark mix as I find that the plants tend to go into a shock at the relative lack of moisture in bark and can die quickly, or suffer from stunted growth. I wait until the new growths have matured with substantial green substance before I repot them in a bark mix. And, I tend to do this in late autumn when they are not under any temperature or light stress. By spring, they will be racing ahead in the bark mix with new root growth and, possibly new canes and/or flower spikes.
One Month Later……….
After one month from the re-seating described previously, note that the pale new growth is now mature and bright green. And, note how the roots are emerging from the growth above the sphagnum moss. This plant will be ready for potting-on into a bark medium in the next few weeks as autumn cools the air in Brisbane.
Epiphytic orchids grow on trees or rocks (lithophytic), where they are dependent on their host for support but not for food.
The majority of Australian epiphytic orchids can be easily grown in cultivation. Most can be grown in Adelaide if the correct cultural requirements are provided. These include controlled glasshouse conditions, shadehouse conditions and, in some instances, in the garden. Only a few species are able to tolerate the cold winter months in Adelaide without extra protection, and all need protection from frost.
CONTAINERS AND MOUNTS
Plants can be grown in pots or mounted on an appropriate substrate. Pots may be either plastic or terracotta. Terracotta pots are porous and dry out more quickly than plastic. If terracotta pots are used, their drainage holes may need to be enlarged to give very good drainage. Plants should be potted into the smallest pot, which comfortably accommodates the base of the plant.
Plants may be mounted on materials such as compressed or natural cork slabs, branches of rough barked trees, black weathered tree fern slabs and pieces of weathered hardwood. Brown tree fern slabs contain substances, which are toxic to orchid roots and are not suitable. Those species that have a pendulous habit e.g. Dendrobium teretifolium should only be mounted.
Most potted orchids require a mixture made up of bark chips (fir or pine), to which may be added charcoal, gravel or polystyrene chips, in which to grow. Bark used should be aged and preferably purchased as graded hammer-milled bark, not shredded bark. Fresh pine bark contains compounds, which are toxic to orchids. Before use fresh pine bark should be soaked in water changed regularly, to remove toxins. This may take 3 weeks. If in doubt as to the freshness of the bark, treat as above to be sure.
Depending on the size of your plant, bark may vary from 5-7mm up to 20mm in diameter, and sieved if necessary to remove fine particles and dust. Other substances such as scoria, leaf mould and coarse grit may also be added according to the requirements of the particular species involved. Whatever the substrate, be it a slab or potting mix, the essential thing with all epiphytic orchids is to always provide good drainage for the plant’s root system. This ensures no, or minimal, root rot of plants.
Repotting is necessary when the potting mix breaks down resulting in poor drainage, the medium goes stale or when the plant over grows its container. The best time to repot is during the spring, after flowering, when the plant starts to actively grow again. Try to repot every 2-3 years.
Potting on: If the plant has overgrown its container and the mix has not deteriorated, it can be potted on into the next sized pot with minimal disturbance to the root system.
GROWING ENVIRONS, HOUSING
Several species may be grown outside in Adelaide, provided they are given a position sheltered from frosts and hot drying winds. They should receive daily supplementary watering during the summer. They may be tied on to trees with rough non-deciduous bark or grown on rocks. Microclimates can be created in areas of the garden using screens for protection and other plants to help maintain a humid atmosphere.
Bush house, Shadehouse
These structures are built to give protection from frosts, strong winds and sun and to provide extra humidity for plants. They may be covered with shadecloth or tea-tree and should have a solid south wall. They provide protection, but still allow for good air circulation around the plants. A water impervious roof, e.g. fibreglass or polycarbonate sheets, will protect plants and flowers from excess water in the winter.
An unheated glasshouse gives more protection to the plants, achieving higher temperatures during winter days, and better humidity. It may be made from glass or other materials such as fibreglass or polycarbonate sheets. Additional shading with shadecloth or paint is necessary from October to March-April. Adequate ventilation must be provided, by using ventilators under the benches to let in fresh air, and roof ventilators to let out hot air. Alternatively, air circulation can be achieved using fans. All orchids love fresh air.
All plants need to be watered frequently from October to April, during the growing period. Most species require watering once a day or twice a day if the weather is particularly hot or drying. Ensure that plants dry out between waterings. During winter, watering once a week should be sufficient for plants in a glass house environment, although plants which are mounted may be misted (a very fine spray) more frequently. Water early in the morning of winter days to ensure that the leaves of the plants have dried off by night. Water lodging in leaf axils in cold, comparatively still conditions, renders that area liable to fungal attack. Humidity may be maintained by watering the floor and under the benches, particularly in summer.
Rainwater, if available, is preferable to mains water, which can. In some cases, increase in salinity to a level, which is harmful to good plant growth.
To promote healthy growth of all epiphytic orchids, a supplement of half strength liquid fertiliser every two weeks may be used during the growing season of the plant, i.e. November to April. Mature potted plants can be sparingly fertilised with slow release pellets. Too much fertiliser will lead to a salt build up (especially in charcoal), which will harm the plants.
Pests will become a problem in any shadehouse or glasshouse if the grower does not keep a watchful eye out for them. The shadehouse or glasshouse should be kept free from weeds, decaying organic matter and rubbish, as these are the places where pests feed and accumulate. Overcrowding of plants will also encourage pests to thrive.
Pests can be easily removed by squashing if they are in small enough numbers. A pest strip hung in the glasshouse successfully controls many pests. Unfortunately the environment of a glasshouse, which suits orchid culture, also provides a suitable environment for the spread of pests. Poisonous chemical sprays should only be used after non-toxic preparations have been unsuccessfully used. These chemicals also destroy the natural predators of insect pests, upsetting the natural balance.
Caution should be used when handling chemical sprays as many are very toxic to the user as well as the pests. The manufacturer’s directions and warning labels should be read carefully and recommended strength adhered to strictly.
Australian epiphytic orchids are generally disease free. Fungal infections may occur, susceptible areas being new growths, especially in young plants. These can be kept to a minimum by maintaining good air movement and avoiding water remaining in leaf axils for too long. Broad spectrum fungicides are suitable to control severe infections.
Removal of any dead leaves, pseudobulbs, etc, not only enhances the aesthetics of the plants, but also lessens the chance of further deterioration. These areas are also the places where pests may accumulate or diseases harbour.