The most common
insects that plague marijuana indoors and outdoors are thrips, mites,
whiteflies, fungus gnats, budworms, and caterpillars. Of these, mites
are most prevalent in indoor grow rooms; outdoor growers generally find
that leaf-eating insects like caterpillars and budworms are their most
threatening insect pests.
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White Fly
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Mites are tiny, mobile,
hardy, and vicious. They travel from grow room to grow room
on infected clones and on the bodies and clothes of people
who have come in contact with mites. Mites live in nature
and on dogs. Approximately 60% of BC's indoor grow rooms are
infected with mites.
Mites puncture leaves and
gorge themselves on plant juices. In the early stages of
infestation, they produce little evidence of their presence,
although they can be detected by careful examination of leaf
surfaces with a magnifying glass. Look for yellow or white
spots on both sides of the leaves. The spots radiate along
leaf veins, and are evenly spaced.
In advanced stages, spider mite infestations are easily
diagnosed, because the mites build white webbing which
encapsulates plant sections.
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Non-web leaf damage caused by mites can be mistakenly diagnosed as leaf
spotting caused by thrips. Thrips are larger than mites with a more
linear body shape. They bite leaves and create white or yellowish marks
on them, but the marks are more clustered and solidly discolored than
those left by mites. Thrips leave black fecal debris on leaves and in
floral clusters.
Whiteflies are more easily seen than thrips or mites because they fly
around plants, especially when plants are shaken by gardeners or air
movement. As their name implies, whiteflies are pure white, and are
about the size of the head of a pencil lead.
Whiteflies drink plant juices and leave residue on plant surfaces that
provides sustenance for harmful fungi.
Fungus gnats and related species such as
the crane fly infest soil and root zones. They feed on
roots, which causes a decrease in plants' ability to uptake
nutrients. Gnats are tiny, mobile, and dark. Crane flies
resemble mosquitoes.
Budworms and caterpillars are problems primarily for outdoor
growers. Budworms burrow into ripe floral clusters; they
also spin webs around floral clusters, although this is
infrequent. They eat floral clusters from the inside out,
and their activities provide a vector for a pervasive
cannabis fungal disease known as botrytis or gray mold.
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Leaf infected by a mosaic
virus
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Leaf-eating caterpillars are less difficult to detect than budworms
because they spend most of their time on leaves. They often
manipulate leaves before eating them; their feeding habits include
eating small sections of leaf in between leaf veins, or eating large
chunks of leaf outright.
Mite
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No fun fungi
Although healthy root zones and leaves often contain
beneficial fungi and bacteria, other forms of fungi and
bacteria are damaging to cannabis plants.
The most pervasive fungal invader is botrytis, otherwise
known as gray mold. This fungus is particularly dangerous
because it is virtually undetectable in early stages, and
because it attacks the ripest, fattest buds from the
inside out.
Botrytis waits until cannabis flowers are dense and well
developed, then it infests the buds near the core of the
flower at stem level, and quickly produces gray garbage that
destroys the bud's vigor and appearance. Gray mold and other
pathogens can also affect harvested cannabis, even when
harvested material is placed in a freezer.
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Gray mold causes problems indoors and outdoors, particularly where
humidity levels are above 50%, with poor aeration of plant tops. Downy
mildew is almost as prevalent as gray mold, although it causes less
damage and is harder to detect. It originally appears as faint whitish
or yellowish spots on leaf tops, with corresponding bumps on the
undersides of leaves. Leaves curl up and mutate as the mildew takes
hold.
Powdery mildew is not downy mildew; it first appears as small bumps on
the top of leaves; soon, the leaves look like they are covered in dusty
grit. In some cases, powdery mildew can superficially resemble resin
glands.
"Damping off" molds attack seeds before and after they have been
planted. The molds also attack emergent seedlings and seedlings that
have attained as much as six inches in height. Damping off can keep
seeds from sprouting at all. Or, they kill sprouts by rotting their
stems at the base.
Viruses and
bacteria
Viruses affect plants, not just people, and some viruses can
jump from people to plants and back again. Among the most
prevalent cannabis viruses are "streak" and "mosaic" viruses
that cause swirling white and yellow discolorations on
leaves. The discolorations are almost artistic, but soon,
the leaves wilt.
Several species of bacteria also attack cannabis. Most of
these bacteria manifest themselves as "blight" diseases that
create spots on leaves, wilting, rotting, weak stems, and
rapid decay of harvested material.
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Plant infected with mites
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Insect elimination
The first line of defense against insects and other plant invaders
is to prevent them from getting near plants. Indoor growers can
achieve this by carefully filtering air intakes and other vectors.
Outdoor growers have a harder time preventing insects from alighting
on plants.
All growers should examine plants daily with a magnifying glass,
looking for insects and insect damage. Grow environment sanitation
is also important; growers should maintain a pristine environment:
remove all plant debris, use sterilized equipment, do not bring dogs
into grow areas, make sure water and water reservoirs are
disinfected, do not enter a grow area in the same clothes after
visiting an infected grow area.
Fungus Gnat
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If spider mites establish themselves in a
grow area, it is virtually impossible to get rid of them
without removing all equipment and plants from the area and
totally cleansing the space. Beneficial predatory mites
placed on plants before spider mite infestations take hold
can help defeat spider mites. Spraying mite-infested plants
with organic soap-garlic-cinnamide sprays also kills mites.
The use of toxic poisons on cannabis, at any stage in its
growth cycle but especially during flowering, is dangerous
to the consumer and unethical.
Thrips can be controlled using predatory
organisms and sprays, especially sprays containing
pyrethrum, nicotinic acid, organic soap, and garlic. Thrips
often rely on grow medium for their reproduction, so be sure
to treat grow mediums as well as plants. Whiteflies like the
color yellow; one control for whiteflies is a commercially
available yellow strip coated with sticky material that
attracts whiteflies and then traps them.
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Parasitic wasps released before whitefly infestation can keep
whiteflies from taking over a grow situation. Sprays containing
pyrethrum and organic gardening soap kill some whiteflies,
especially when they are airborne. Whenever using sprays, be sure to
spray the underside of leaves thoroughly, as this is where many
pests live.
Fungus gnats thrive in over fertilized,
over-watered grow mediums, especially those where organic fertilizer
high in nitrogen has been used. Gnats can be killed by disturbing
soil, heating soil, by predatory wasps, and by applying insecticidal
soap, neem, rotenone, and garlic oil to gnat infestations.
Budworms and caterpillars can be controlled by
shaking plants several times a day to dislodge the insects.
Preventive sprays containing insecticidal soaps and organic toxins
can be used selectively during vegetative cycle, but extreme care
must be taken during floral cycle.
It is usually best to watch for the gray mold-like symptoms of
budworm and remove the bud or section of bud where the worm resides,
rather than to risk spraying any kind of toxin on a dense,
harvest-ready bud.
Virus,
bacteria and mold control tips
High humidity (over 50%) and grow environment
contamination should be eliminated. Grow mediums should
be sterilized and then treated with beneficial fungi
(such as Trichoderma and Gliocladium) and beneficial
bacteria.
Light intensity should be adequate
for penetration deep into plant canopy, both vertical
and horizontal. Plants should be directly in line of
fans and other aeration. In-line charcoal filters and
other traps should be in place on all air intakes.
Strict sanitation controls should be in place for anyone
who enters a grow environment.
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Thrips
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"Boudreaux mixture" can be useful for
controlling gray mold. A spray containing copper, Boudreaux mixture,
and a beneficial organism called Bacillus subtilis is effective
against downy mildew. Spraying with bicarbonate of soda, organic
horticultural oils, and sulfur can kill powdery mildew. Some growers
use sulfur burners to create airborne sulfur treatment against
powdery mildew. Bacteria can be controlled using Boudreaux mixture.
Plant infected from thrips
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Viruses are impossible to kill once
they have infected a plant. A preventive measure to
protect against viruses, other than the generic tactic
of preventing them from entering grow environments, is
to keep plants' immune systems healthy with proper
watering, temperature, root zones, and nutrients.
If molds, fungi, viruses or bacteria
take hold in a grow environment, it may be necessary to
remove affected plants completely. Near-harvest buds
affected by most insects, pathogens and diseases can be
partially salvaged by using them to make water hash.
Otherwise, all plants or plant parts affected must be
immediately removed and destroyed, and any tools,
clothing, or other materials that came in contact with
the affected plants must be removed, sterilized or
destroyed.
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how to grow marijuana
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Alabama
