I write this article at a time when we remain enjoying crappy weather and when hopefully, disease and fly populations remain low. With a little luck, by the time it is printed, warmer temperatures will be imminent.
In general, last year was good for low fly and disease problems. Unfortunately, Mother Nature often conforms to Sod's Law, so beware.
Some Maths: The rate of a population growth at any instant may be given by the equation: dN = rN dt where
r is the rate of natural increase in
t - some stated interval of time, and
N is the number of individuals in the population at a given instant.
The algebraic solution of this differential equation is N = N0ert where
N0 is the starting population
N is the population after
a certain time, t, has elapsed, and
e is the constant 2.71828... (the base of natural logarithms).
Plotting the results gives this exponential growth curve, so-called because it reflects the growth of a number raised to an exponent (rt).
What's this got to do with mushrooms? - The population of both flies and disease follows a similar pattern. The population at any time will also depend upon: a) The original population - (best not to have any.) b) The number of offspring per generation - flies: around 180; disease: millions. c) The number of surviving offspring (and a suitable breeding and feeding environment e.g. mushroom houses = lovely jubbly). d) The time interval between each generation - alas, this can be so short. e) Available routes to suitable breeding grounds - flies and disease = disaster. f) The effectiveness of any treatment - rarely 100%. f) When and how a grower intervenes. The objective of this article is simply to remind growers of the latter point (f).
The Advantage of Acting Promptly: Whether one is considering blotch, flies or familiar spore spreading diseases, one needs to act sooner rather than later. Referring to the graph above, the earlier prevention is applied, the lower the subsequent latter population. Thus, by the end of crop, hopefully populations are eliminated or controlled to insignificant levels.
As said, the effectiveness of any treatment is rarely 100%. If a 90% treatment effectiveness exists, this will have a major effect upon the population increase rate but only of real value if this is applied early enough. If applied from the start, the rate of increase will be reduced to a level that generates acceptable populations through to end of crop. The later the treatment is applied, the far greater the risk of unacceptable and unrecoverable levels. Whilst a population may be reduced to 10% at any stage, 10% of 10 = 1 but if applied later, 10% of 1,000 = 100, which would not be acceptable (with a next generation being say, x180 = 1,800) etc. etc..
Blotch: If this is a potential problem this should be treated from the start of crop, not half way through when populations have reached excessive levels. Spore spread diseases: Simply never allow significant numbers to develop and multiply. Identify and treat any infections as early as possible! Flies: Don't wait until populations are "significantly noticeable". Prevention is better than any cure. Disease and flies: By then, you are really up against it.
Summary: The reader may say there's nothing new here and there's not. This is however, a reminder. If problem populations are currently low - before the warmer weather has an effect, give thought to preventative measures sooner rather than later.
Addendum: (For readers who might be interested in my avian exploits.) Again the National Poultry Club Show took place just before Christmas. This year I was not championed for the quality of my cock, however again we won Best of Breed with a very nice pullet. What did I say about Sod's Law at the start? The pullet keeled over two weeks later. We are having second thoughts about entering next year.
