VOLUME 14 :: January—October, 1952 Illustrations shown in ...

26 THE CACTUS AND SUCCULENT Apr/7, 1952
CACTUS CULTURAL NOTES
By A. BOARDER
In the January issue of the Journal I dealt with the sowing of Cactus seeds and as I had written far too much
a portion of my notes had to be omitted. I will now continue the directions and then it will be possible to have
a complete description by referring to the two Journals. Once the seeds are sown the subsequent watering can
be a little difficult. I use a very fine spray and water from overhead, always remembering to test the spray first
to see that it has not become partly blocked when it can send out a strong stream which will blow all the seeds
away. Do not allow the peat surrounding the pots to dry out, but again do not let them stand in water. Raise
the protecting glass each day and if there is any sign of mildew spray with a fairly strong solution of Permanganate
of Potash. The seed compost should have been sterilised, but some of the pod casing may have been present with
the seeds and this can soon form mildew. See that the water you use is not polluted and keep it covered so that
the sun does not cause Algae to form, as this will encourage green to form on the surface of the pots.
You can expect the seeds to germinate in from four to ten days, but a great deal will depend on the genera.
With my usual batch of Mammillaria, Notocactus and Rebutia seeds, I look for germination after about four days
and it is very unusual for many days to go by without some of the seeds showing signs of life. Because of the
different times taken for the germination it is advisable that when sowing you should keep the same genera in one pot.
Once any seeds have germinated in a pot it is essential that the cover glass is kept raised so that some air can
get to the seedlings. If they are kept too close they will probably damp off. This damping off disease, or Black-leg,
is not too difficult to prevent, but it is almost impossible to cure affected seedlings. It can happen over-night and
lack of air and excessive dampness are the main points which accelerate the trouble. Once the seedlings appear
and look to be growing it is not so important to keep them damp, and it is possible to treat them in a similar manner
to mature plants once the plant proper is forming. You must aim at a steady and uninterrupted rate of growth
the whole time, as once a seedling gets a bad check it will be a long time before it starts to grow again. These
checks can be caused by excessive dryness and also from over dampness, but whereas a seedling which has received
a check through dryness can soon pull round ; if the cause has been over-watering the seedling may never recover.
If the seedlings are unshaded and are subjected to strong sunshine this can also cause a check. The plants will
turn red in colour and once this has happened it may be a long while before you are able to get them growing again.
Some people raise their seeds in an airing cupboard or similar place. This will usually produce seedlings which
are weak, pale and spindly and where such plants are badly drawn up they may suffer from damping off. It is better
to raise seeds on an indoor window-ledge shaded from the sun than to do so in complete darkness. Such seedlings
would have to be gradually introduced to the light.
Whilst you are waiting for the seeds to germinate, as long as you keep the cover glasses on the pots it is not
necessary to water very often. It may well be that providing you have watered the soil sufficiently in the first
place no more water need be given until the seedlings are up. Overwatering can prevent germination and cause
the seeds to rot.
I have heard from one or two members that they have been bothered with red spider on their plants. At
least that is what I have deduced from their descriptions. One of the worst plants for this pest is Chamaecereus
silvestris, and the first signs are usually brownish markings at the base of the stems. It resembles a brown or
reddish rust but if examined with a fairly strong magnifying glass a few tiny red spiders will be seen slowly crawling
over a fine web which covers the plant. The spiders suck the sap from the plant and cause tiny scars. Some plants
are more attacked by this pest than others and a close watch should be kept on all Pleiospilos as well as the above
mentioned plant. A certain cure is to spray with a solution of methylated spirit to which has been added one
part of nicotine to forty parts of meth. After about ten minutes the plant can be sprayed with some fairly hot
water to which has been added a little detergent such as Dreft. This will clean away the nicotine which might
otherwise cause some discolouration.
I have made a start at re-potting all my Cacti. This usually takes me over a fortnight and what with other jobs
I am finding that it will take me much longer this year. All my adult plants are re-potted each year and I am sure
that by this means the plants will not only grow well and flower, but it does tend to prevent root-bug, which is
another pest experienced by many members. The presence of this pest can only be seen as a rule when the plant
is taken from the pot. Small specks of white like flour can be seen on the insides of the pot, in the drainage and
among the roots. The actual bug is like a tiny rice kernel. They do harm to the plant by sucking the juice from
the roots. I am positive that an annual re-potting does tend to keep this pest in check as if a plant is taken from