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Fenland Orchid Society |
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Beware the Fibres
To all those who purchased or are using the Ray Creek Coconut potting compost a word of warning.
When you put the dry compost into a container and add water to allow it to swell and become damp you will no doubt do as I did and give it a stir. This in itself is fine but when you come to use the compost I would suggest you ladle it onto your potting bench or tray to allow it to drain off excess water. The reason I say this is, that having put it into the container to free it up you also allow the loose fibrous material to fall to the bottom of your container and if you just use it straight from the container then you will find that you have a thick fibre blanket at the bottom once all the chunky bits have been used.
Take out all you have got swollen and free, once the excess water has drained off you can then mix in the fibrous material. If you use the fibres from the bottom on their own you could find it matting together and holding to much water and so killing your root system and killing your plant so use and mix all you wet and you should be ok. I have spoken to Ray on this little point and he says he mixes the full bale when once wet so problem does not really occur but he will point it out to people who are making up a small amount in a bucket or small container.
I am using it and my plants do seem to be liking it, time will tell.
Red Spider
Stress, a word most commonly used in the manner of humans and how they feel but when applied to plants it is relevant to a plant that is not looking its best. It looks limp or has a tired appearance and it is at this time when it is most vulnerable to insect attack particularly red spider mite attack.
First let’s look at the red spider mite or two spotted mite Tetranchus urticae sometimes even called the glasshouse mite. They tend to breed from spring to autumn. The female of the species tend to live for a month or more and can produce up to 100 eggs. Eggs are in the first instance transparent turning white to a light yellow just before hatching. The resulting hatchling a six legged larvae immediately starts to bite into the leaf it is on and starts to suck the plant juices. They breed on the underside of the leaf so nothing is always apparent until yellow marks start to be seen on the top f the leaf. Having fed on the plant for a few days the larvae goes into a rest period, but at temperatures around 20/21 degrees it has a life cycle of 12 days, so you see it can multiply rapidly. It breeds much slower at cooler temperatures of 10 degrees it then can take 55 days to go through a life cycle.
A very fine spider web may be seen under the leaf that is infested and this is usually seen after spraying as it tends to hold in place small droplets of water. Spider mites do not like cold water but we tend to keep our water at the greenhouse temperature so as to be kinder to the plant.
They are most difficult to kill and clear from a plant or greenhouse. First remove and burn all infected parts of the plant if the infestation is bad. Then there are a number of products on the market for controlling/getting rid of red spider mite. Growth Technology do a spray able liquid which you mix according to the instructions on the bottle and then apply to the plant making sure you give the underside of the leaves proper attention. Scotts bug clear coming in a ready mixed spray bottle can also be used in the same way giving the underside of the leaves a good wetting. There are others but do read the labels as some can have health risks for some individuals when used in enclosed spaces. A mask and gloves and maybe some form of eye protection should always be used when applying chemicals in your greenhouse.
There is also on the market a more organic way of getting at the red spider mite if you do not wish to risk chemicals. This involves the use of another mite but a beneficial one, one that eats the red spider and it’s larvae.
Phytosieulus persimilis this is the name of the plant friendly mite, shiny orange and a fairly fast mover. Eating eggs, larvae and adult spider mites it will soon be removing the threat to your plant. A temperature of 18 to 20 degrees allows this predatory mite to work at its most efficient. Used between April and September it will chomp through the red spider mite colony. They reproduce at twice the rate of the red spider mite so are soon clearing up more of the bad mites. High humidity gets them working better so as soon as you see red spider send for your rear guard action mite and up the humidity A second application may be necessary just to be on the safe side but it must be worth it. Though not cheap they can be purchased in many ways some come in a shaker others are supplied with vermiculite granules but whichever way you buy they get to work straight away.
A third way of controlling red spider is by attacking their body shell. This is a waxy shell or epicuticle that repels water but through which they breathe when young. The use of neem oil mixed as per directed will coat the shell and so block all ways in for oxygen in both young and old mites and basically suffocate them. A mixture of agricultural soaps would have a similar effect.
All methods will work but some will work better than others due to each having their own particular system setup. Warm dry conditions favour the red spider mite so at these times keep up your humidity to try to keep at best minimal infestation. A spray of cold tap water may be a bit of a shock to your plant but it will get at the red spider and anyway the extra bit of calcium from the tap water may be beneficial to Your plant. A carefully applied chemical or a predatory mite no matter which way you move there is no better cure than being on your guard and keeping your conditions right for your plants and not their enemies.
A slapdash pest control method never kept a clean greenhouse so remember when you exhibit plants do fully inspect under as well as over the leaves, try to be as sure as best you can that no live stock will be transferred to anyone else's plant when they are in close proximity at a show or even on our own show table or for that matter when you wish to give a plant or piece of a plant to a fellow grower. Be keen, clean and green.
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May 09 Abridged |
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Angraecum Sesquipedale |
