Probably the worst problem in growing chrysanthemums these last two years has been trying to control blackfly (aphid gossippi). Last year 1991 my flowers were simply hoaching with blackfly and it was impossible to show a large proportion of the blooms. I didn’t say much about it to my fellow growers as I thought they wouldn’t believe me.
Now that they have had experiences of the pest they appreciate the task of controlling them.
This last season I was determined to try and keep my plants as clean as possible and embarked on a weekly spray routine which rang the changes and kept the plants scrupulously clean. Using a 15 litre capacity knapsack sprayer which forced the spray well into the foliage of the plants. I would not go back to the traditional or usual one gallon capacity sprayer which simply doesn’t have the pressure and cover of the knapsack type.
Since it had been reputed that ordinary insecticide had little effect on blackfly larvae I decided to try to get and use some form of paraffin and soap mixture something like what was used by the foremost growers years ago. I made up a paraffin and soap mixture and used it to reasonably good effect up to and after calyx split when the bud bag was immediately placed over the bud. I also removed the bracts and small leaves under the buds.
My flowers were not completely free from blackfly but whether
it was the smell of paraffin or the soap inhibiting their breathing
there were only about ten bags infested with blackfly. Earwigs
also disliked it and come out of the canes backwards, at speed!
At the end of the season when the last flowers had blackfly I
began to wonder if the mixture becomes stale on standing and should
always be used freshly made. Hopefully someone will improve on
the mixture possibly with additional soap and or paraffin or whisky
and let us all know about it.
The Parasoap Mixture or Insecticide used is:
One desert spoonful of paraffin and one desert spoonful of washing
up liquid placed in a bucket which is marked at one gallon capacity.
Run the hot water tap until the water comes really hot and fill
the bucket to the one gallon mark. Cover the bucket and place
outside to cool, once cool it is ready for use.
Over the years I have gleaned and recorded information on many aspects of chrysanth growing and the following are two paraffin/soap mixes which I declined to use for reasons I shall give in my comments.
1. J. H. Goddard’s (1952)
Soft soap and paraffin insecticide.
A wineglass of paraffin and a lump of soft soap should be added
to a gallon of water and mixed thoroughly. This insecticide should
be applied towards evening if possible.
My comment on this is - there are many sizes of wineglass and
all sizes of lumps.
2. Paraffin and soap insecticide
(Garden News 21/1/89).
Collect one gallon of rainwater, boil one pint and stir in 2ozs
of soap flakes. Mix also l6ozs of liquid paraffin with an egg
beater. Add the rest of the rain water, beat the mixture thoroughly
and the emulsion is ready for use.
My comment - a lot of work for one gallon of spray.
The subject of controlling blackfly was discussed at length at
the N.C.S. (Scottish Group) Conference at Perth on 17th October
1992 by the speakers Mike Robbie and Bill Wade and the attending
members. We all know that chemicals which control blackfly are
not available to amateur growers so we have to be inventive and
use what is available to us. To stop blackfly overwintering in
the soil growers are treating their soil with Jeyes Fluid, Armillatox,
etc before and after digging.
I have also heard about home made concoctions such as boiled rhubarb leaves. I had no directions or recipe but decided to have a go. This turned out to be some performance which the local lads got a laugh at.
The first problem was my wife who does not thole me with my concoctions near her kitchen and is extremely fast on the nose. I had noticed the fine big deep pot for jam making and never miss an opportunity when anything is beneficial to chrysanth growing. The opportunity to boil the rhubarb leaves presented itself when she announced she was going shopping. I immediately suggested the kitchen window should be opened to help clear the “alleged” smell of jam making the previous day, the window was duly opened.
I used scissors to cut and shred 4.5Ibs of rhubarb leaves which was put into the jam pot in 1.5 gallons of water and boiled for 15 minutes after which it was allowed to cool in a bucket. The jam pot was washed thoroughly and returned to storage . . . . quickly!
Next day I put the rhubarb brew through a fine sieve which was a long messy job since the leaves were boiled to mush. I ended up with one gallon of liquid which I haven’t used yet as I’m afraid to use it straight. Has any grower any ideas on how to make and use rhubarb brew because I haven’t. I wouldn’t be a bit surprised if it was banned . . . . like me . . . . as I’m sure to be.