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Abstract On Rose Diseases Essay, Research Paper
title = abstract on Rose diseases
Multi-Purpose Fungicide Daconil 2787? Plant Disease Control
This product is widely used for broad spectrum disease control on lawns,
ornamentals and listed
fruits and vegetables. Controls many foliar diseases such as: rust, black spot, leaf
anthracnose and powdery mildew as listed on the label. Also controls conifer
diseases and lawn
diseases such as brown patch, red thread, rust and dollar spot. Can be mixed with
specified on the label to make a multi-purpose spray.
WHAT IS POWDERY MILDEW?
Powdery Mildew looks like white fuzzy powder that accumulates on leaves and stems
predominantly in spring, and again to a lesser degree in fall. It is actually a fungus that
is spread by
millions of microscopic spores. It imbeds itself into tender new growth and feeds on
the sap of the
plant. By the time the naked eye can see the white ‘powder,’ it has already invaded
the plant tissue
and is feeding and reproducing at a rapid pace. As it spreads itself on the surface, it
the cells of the plant leaf, leaving the leaf rippled and curled.
Mildew spores are everywhere in the garden – in the air, the soil, on debris and on
plant surfaces -
ready to sprout when the environment is just right. Warm days (50?-80?F) and cool
elevated humidity and resultant dew provide ideal conditions. Though humidity
growth, it grows on DRY plant surfaces, unlike blackspot which requires immersion in
about seven hours in order for infection to take place.
Tender new growth needs a chance to ‘harden’ and develop its waxy coating that
of a barrier to fungal growth. Therefore, the rosarian must provide protection for new
on a weekly basis.
CONTROLLING POWDERY MILDEW
Controlling mildew doesn’t have to mean spraying the planet into oblivion. It includes
cultural practices and something as simple as WATER.
GENETICS: While rose hybridizers are chastised for breeding OUT fragrance, what
they are trying
to accomplish is breeding IN disease resistance. For scientific reasons beyond
explanation here, rose
genes don’t contain both features – it’s one or the other. Hence, you can expect either
with little disease resistance, or clean plants with little fragrance. Plants with glossy or
are less susceptible to mildew, as the leaf surface is harder for spores to penetrate.
possess a high degree of disease and pest resistance. Where mildew is a constant
problem, the choice
in plantings can help prevent the need for extensive maintenance.
CULTURAL PRACTICE: Planting bushes with sufficient space between them and
away from walls
and fences will provide good air circulation which reduces the chances for mildew.
The annual pruning event plays a major role in disease prevention. Stripping leaves
from the bush at
pruning time, and cleaning up debris in the garden contribute to a cleaner
spraying will at least wipe out last year’s spores, leaving only this year’s to contend
with. Keeping the
centers of the bush open during the growing season will aid air circulation.
Avoid the use of other plant materials with high mildew susceptibility, such as
tuberous begonias. Apply a thick layer of mulch in early spring to cover spores in the
soil that may
have wintered over. WATER is perhaps the most misconceived element surrounding
mildew. Many gardeners still subscribe to the belief that you should NEVER get rose
On the contrary, a high-pressure spray of water will remove mildew spores that
themselves yet, and prevent them from germinating. Higher incidence of mildew
during periods of
rain is caused by the moisture in the air and soil – increasing the humidity that
promotes mildew -
not by water on the leaves. Similarly, watering early in the day will allow the soil
surface to dry out
a bit before the cool night temperatures arrive, reducing humidity from moist soil.
PREVENTION IS THE ONLY CURE
Once powdery mildew is apparent to the eye, it can’t be eradicated. It simply must be
Prevention is achieved by coating the plant tissue with something that provides a
barrier to prevent
fungus from gaining a foothold and invading the plant tissue. Growth is so rapid in
spring that the
leaves unfolding THIS week won’t be protected by what you sprayed LAST week.
This is the reason
you find application schedules of every 7-10 days on most fungicides, and the reason
follow that schedule.
The choice of what the SOMEthing is that you choose to spray is widening.
Fungicides are the most
widely used because they are chemically formulated to specifically combat fungus
reports of non- toxic, environmentally-friendly products such as baking soda and
are proving very encouraging also.
FUNGICIDES are any of a number of chemicals labeled to combat powdery mildew,
and do so by
interfering with its metabolic life process, rendering it unable to grow and spread.
must be in place on the plant before the spores arrive, they do have systemic action -
move into the plant tissue – providing a residual effect for a short period.
Fungicides are available in many forms – liquids (mix readily with water), emulsifiable
(a thicker, usually milky substance), wettable powders (require thorough mixing prior
application). Each has its own properties, all are effective. Most, however, have a
degree of toxicity to humans. Extreme caution should be used to cover eyes, skin and
hair, and use a
painter’s mask or respirator during application. They are mixed at various rates,
tablespoon per gallon of water, and require application every 7-10 days.
BAKING SODA: “New research shows that simple baking soda is a powerful weapon
fungus-caused rose diseases”, wrote Kristi Clark in her September 1992 American
In a world that is becoming increasingly aware of environmental concerns, more
attention is being
paid to finding alternative measures to widespread chemical use. Sodium
(grocery-variety baking soda) was tested originally to determine its effectiveness in
blackspot. During the experiments, it was noticed that no powdery mildew was found
on any of the
Controlled experiments were conducted for some three years, using sodium
potassium bicarbonate in various combinations with insecticidal soap, Sunspray?
oil, or only water. The result: both diseases were subdued by a weekly spraying of
either sodium or
potassium bicarbonate at 3 teaspoons per gallon of water, combined with Sunspray at
per gallon of water. The bicarbonates eliminated the fungi, but addition of the
Sunspray provided a
spreader-sticker action that increased its performance.
Sunspray is available commercially as Safer? Sunspray. As Clark cautioned, do not
concentrations of the solutions, as leaf burn may result. Rain or overhead watering
may wash the
solution off, reducing its effect.
ANTI-TRANSPIRANTS are another group of substances that hold promise as a
of controlling powdery mildew (as well as pests). Anti-transpirants are emulsions and
polymers that were developed to form an impermeable film on plant surfaces to
moisture loss. Several brands are available; look for a white liquid, about the
consistancy of milk.
They are widely used on cut Christmas trees to retard drying and needle drop, and on
provide protection from drought, heat, wind and transplant shock. Since the thin film
transpiration of moisture – both in and out of the leaf – it makes sense that it would also
fungus spores from permeating the leaf surface.
Some rosarians have used antitranspirants in combination with fungicides, and feel
works better than fungicide alone. Others have used it entirely alone, and find that it
works very well
all by itself. Packaging directs us to water plants well and allow them time to take up
before spraying. Since anti-transpirants are NOT yet labeled for disease protection,
there is no
accepted formula for application. They come in various concentrations that would
require more or
less dilution – anywhere from 1 tablespoon to 1/2 cup per gallon of water. Again,
frequency is not
addressed … once a week … once a month? At this stage it’s sort of experimental. If a
residue is left
on the foliage (objectionable to you as an exhibitor) then reduce the ratio.
Whether we choose the fungicide method or the non-toxic approach to controlling
probably depends upon the degree of severity we encounter on a regular basis.
Regardless of the
product selected, it must be used on a regular basis in the proper dilution to prevent
without damaging plant tissue.
What is Blackspot?
Blackspot is a plant disease caused by a fungus (Diplocarpon rosae) that is generally
usually a source of major problems. Blackspot looks like circular black spots with
on the top side of the leaves. The tissue around the spots or the entire leaf may turn
yellow and the
infected leaf may drop off. Plants with a severe case may lose all of their leaves if not
production is often at a minimum and the quality of bloom suffers badly.
High humidity is one factor that helps the spores to germinate. The spores germinate
in 9-18 days on
a moist leaf at 70-80?F temperatures. The spores can be spread by splashing water
and by the
Rosarians themselves. The spores are wind-borne only in water drops. The spores
can be spread on
clothing, tools or even your hands, but the way it is spread most often is by infected
leaves that have
wintered over in the rose bed.
Blackspot can be satisfactorily controlled by spraying with a good fungicide every
seven to ten days
(read the label and follow the directions). There are also a number of measures that
should be taken
to keep from getting and/or controlling the disease. Avoid watering in a way that
splashes water up
on the leaves and avoid watering late in the evening with a hose or sprayer. Make
sure to clean up
the beds completely of all leaves or stems to help keep the disease from wintering
over. Always have
good ventilation through the plant and good soil drainage. Apply fungicides after a
rain to keep
down spores. Put the plants on a spray schedule and spray with a fungicide that gives
such as, Manzate?, Maneb?, Daconil? and Lime-Sulfur compounds.
There are also organic methods of controlling Blackspot. Baking soda has been tried
as a cure and
as a preventative measure. It was found that using baking soda and spray oil mixed
with water as a
spray can damage roses if it is not mixed in the proper proportions. It was also found
soda gave only moderate control of Blackspot, but appeared to be effective as a
is a new product coming on the market that has been used by our local Rose Society
that does show
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