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Desiccation
Pathogen - Low soil moisture or low humidity
Symptoms - Plants may wilt, although this is unusual
for most bromeliads due to their rigid leaves. Sometimes the leaves
will curl. Patches of tan or dead tissue form on the leaf edges
and tips.
Control - Make sure plants receive adequate irrigation.
Keep humidities high to reduce development of the leaf burn even
when soil moisture is high. Reducing the light level and temperature
can also reduce desiccation damage when humidities cannot be maintained
at sufficiently high levels. |
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Erwinia
blight
Pathogen - Erwinia spp.
Symptoms - A blackened, wet, slimy spot generally
starts at the base of the plant. Plants wilt, collapse and usually
die. A rotten, fishy odor may be present on severely rooted plants.
Control - Remove and destroy infected plants as
soon as they are found. Keep watering to a minimum and avoid splashing
since this can spread the bacterium to other plants. Irrigate early
in the day to allow rapid drying of the foliage which reduces the
ability of the bacterium to infect. Be sure to obtain an accurate
diagnosis of the problem since several of the diseases caused by
fungi appear similar. Do not use bactericides for control of Erwinia
on bromeliads since they are not effective. |
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Helminthosporium
leaf spot
Pathogen - Exserohilum rostratum
Symptoms - Initial spots are pinpoint, water-soaked
and yellow. They are circular (1/16 to 1/8 inch diameter) to elliptical.
Individual spots become sunken with brown centers and often have
a yellow border. Under optimal conditions, spots merge to form large
dead areas causing affected leaves to collapse and hang limply on
the plant. This disease can be very serious on small plants when
they are transplanted, since wounding creates more infection sites.
Control - The cultural controls listed for Erwinia
blight are also effective for Helminthosporium leaf spot. Fungicides
which control this leaf disease included chlorothalonil (Daconil
2787), mancozeb (Dithane T & O) and zineb (Ortho Zineb 75WP).
Check fungicide labels for legal uses on bromeliads. |
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Fusarium
rot
Pathogen - Fusarium sp.
Symptoms - Dieback, root and leaf rot may occur
as a result of the Fusarium infection. Spots are generally tan and
may be dry at times and appear sunken. The orange or tan colored
spores of the pathogen form in these areas, and they spread easily
by water or air since the spores are light weight. A water-soaked
rot at the soil line is common as well as 1/16 to 1/8 inch roughly
circular spots on the stem.
Control - Use the same cultural controls as listed
for Erwinia blight. Thiophanate methyl (Domain or Cleary 3336) and
mancozeb (Dithane T & O) are effective in controlling Fusarium
diseases. Reduction of water applications greatly reduces spread
of the pathogen to aerial portions of the plants, thus reducing
disease severity. The majority of bromeliads are susceptible to
this disease with infections occurring with or without obvious wounding.
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Pythium
root rot
Pathogen - Pythium spp.
Symptoms - Bromeliads infected with Pythium spp.
turn a dull gray-green and may wilt. Stems become rotted at the
soil line and upper portions of the plant collapse. Roots are darkened
and mushy and generally sparse.
Control - Use pathogen-free pots and potting media
and grow plants on raised benches. Over-watering plants may predispose
them to attack by root-rotting fungi. Soil drenches with the combination
of etridiazol and thiophanate methyl (Banrot), etridiazol (Truban
and Terrazole formulations) or metalaxyl (Subdue 2E) each aid in
control of stem and root rots caused by Pythium spp. |
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Rhizoctonia
aerial blight (Rhizoctonia solani)
Symptoms - A mass of brownish mycelia can cover
infected plants. Growth of mycelia from the potting medium onto
the plant can escape notice and give the appearance that plants
have been infected from an aerial source of inoculum. Close examination,
however, generally reveals the presence of mycelia on stems prior
to development of obvious symptoms. Rhizoctonia mycelia are usually
reddish-brown in color and have the consistency of a spider web.
Under wet conditions, Rhizoctonia spots are gray or black and mushy.
Control - Chemical control of diseases caused by
Rhizoctonia has been investigated on many plants using a variety
of fungicides. The fungicide most widely for soil drenches control
of Rhizoctonia diseases is thiophanate methyl (Domain or Cleary
3336). Cultural controls are the same as those listed for Pythium
root rot. |
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Rust
Pathogen - Puccinia tillandsia
Symptoms - Rust disease is easily recognized because
of the reddish-brown or yellowish-brown pustules which occur on
leaf undersides. The spots first appear white or light yellow when
viewed from the upper surface. Most rust pustules form on the undersides
of leaves but some can be found on leaf upper sides.
Control - Rust diseases are inhibited by frequent
rainfall or irrigation and high temperatures. Fungicides for rust
control on some ornamentals include chlorothalonil (Daconil 2787),
ferbam (Carbamate), triadimefon (Bayleton) and mancozeb (Dithane
T & O). Few fungicides are labelled for use on bromeliads so
be careful to check labels for legal uses on your plants. |
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Slime mold
Pathogen - one of many genera of myxomycetes
Symptoms - Small tan or creamy colored structures
sometimes similar in appearance to rust diseases found anywhere
on the plant surface. They are easy to scrape off the leaf surface.
The cause of this problem is slime mold which is a saprophytic fungus
that can grow on any surface including the potting medium, pots
and the plant leaves.
Control - Fungicides have not been found effective
in controlling slime molds. Keep pots as dry as feasible for good
plant growth and grow on raised benches only. |
