Probably the most common disease for lily growers,
botrytis is a fungal disease which affects the stems,
leaves and in extreme cases, the flowers and buds of
lilies as well. It is not restricted to affecting lilies,
it affects a wide variety of other plants and crops
as well, such as canola and annual bedding plants.
Botrytis is spread by spores located on the undersides
of the leaves, on the ground, and in old garden
debris. The spores are spread by wind and rain or water
splashing, and are encouraged by damp, wet and humid
conditions. Often botrytis starts after frost, hail
or other exterior damage is experienced by the plant,
or during extended periods of rain and damp weather.
Once it starts, and if favorable conditions persist,
it moves like wildfire through the lilies. Beginning
as a small white or brown spot on a leaf or bud, the
spot grows into a larger brown spot with a lighter center,
until it engulfs the entire leaf and then the stem and
buds, if action is not taken. The damage can be held
back or avoided using preventative sprays of chemical
or organic nature.
This
fungal disease is limited to the plant growth above
ground, and does not carry over into the bulb from year
to year. How does botrytis affect bulb growth? If the
stems are completely affected and totally brown to the
tip early in the summer, the bulbs will simply not increase
in size, and it will sprout and grow again the next
year. Botrytis only affects bulbs if experienced 3 years
in a row, under extreme conditions where the stems are
totally brown by mid summer. The following year the
bulbs will fail to sprout, their quality seriously deteriorated
due to the ongoing disease.
To prevent botrytis it is best to remove and burn all
garden debris, meaning dead stems and leaves, every
season. Spray the ground around your lilies early in
spring with a preventative spray such as our Baking
Soda recipe, or Bordeaux Copper Spray, a commercial
fungicide readily available at most garden centers.
Since the chances of botrytis infection increases after
damage to the stems or leaves, spray immediatly after
frost or hail damage has occured, and every 2 weeks
thereafter, until the middle of August, when stems may
begin to naturally die down. If you are lucky enough
to have access to farm chemical sprays, the most recommended
product to use for botrytis on your lilies is called
ROVRAL, and works very well in effectively stopping
the spread of botrytis once applied.
