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How to Manage Pests
UC Pest Management Guidelines
Floriculture and Ornamental Nurseries
Damping-off
Pathogens: Rhizoctonia solani, Pythium spp., and others
(Reviewed 1/02,
updated 1/02)
In this Guideline:
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SYMPTOMS
Seedlings rot at soil line and are killed. If problem is caused by
Pythium, it usually begins at root tips.
COMMENTS ON THE DISEASE
Damping-off is the name given to seedling diseases most often caused by fungi.
As the name implies, the disease is associated with damp conditions. Some
Pythium species are favored by cool, wet conditions while Rhizoctonia
can cause disease under somewhat drier and warmer conditions. ELISA test
kits are available for detecting Pythium and Rhizoctonia fungi.
MANAGEMENT
Vigorous seedlings grown from the best seed and under ideal light and
temperature conditions may survive in the presence of these fungi while
seedlings low in vigor will succumb under unfavorable conditions. Damping-off
can be minimized by providing good drainage (raised beds, leveled fields),
careful irrigation, planting when soil and air temperatures are favorable for
rapid seedling emergence, proper depth and spacing of planting, seed
treatments, and drenches of soil fungicides.
| Common name |
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| (trade name) |
Amount to Use
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SEED TREATMENT |
| A. |
STREPTOMYCES GRISEOVIRIDIS |
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(Mycostop) |
0.08 oz/lb of seed or 5g/kg of seed
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COMMENTS: For control of seed rots, root and stem rots,
and wilt diseases of ornamental crops caused by Alternaria, Fusarium,
and Phomopsis; also suppresses Botrytis, Pythium, and
Phytophthora. May be used for both field-grown and greenhouse
ornamentals. |
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SOIL FUNGICIDE - Pythium spp. |
| A. |
MEFENOXAM |
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(Subdue Maxx) |
Label rates |
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COMMENTS: The granular formulation may be applied preplant
or the liquid formulation can be applied as a drench at planting.
Mefenoxam is water-soluble and readily leached from soil. It is absorbed
primarily through roots and is translocated in the plant through the
xylem. |
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SOIL FUNGICIDE - Rhizoctonia solani |
| A. |
IPRODIONE |
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(Chipco 26019) |
0.4 lb/100 gal water |
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COMMENTS: Apply as a drench at seeding at the rate of
1-2 pt/sq ft |
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| B. |
PCNB |
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(Terraclor) |
0.5-1 lb a.i./1000 sq ft |
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COMMENTS: Insoluable in water and must be thoroughly mixed
into the top 2 inches of soil. Some seeds may be inhibited by this
fungicide. |
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| C. |
THIOPHANATE-METHYL |
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(Cleary's 3336F, FungoFlo, etc.) |
20 fl oz/100 gal for 800 sq ft bench area |
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| D. |
TRIFLUMIZOLE |
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(Terraguard) 50W |
4-8 oz/100 gal |
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COMMENTS: For use in enclosed commercial structures
only; less effective against Rhizoctonia than other materials.
Apply as a soil drench at 3-4 week intervals as needed. |
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SOIL FUNGICIDE - Pythium spp. and Rhizoctonia
solani |
| A. |
TRICHODERMA spp. |
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(BioTrek) |
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COMMENTS: Formulated as a seed treatment, a soil fungicide,
and a nursery drench. This biological fungicide may provide some protection
against both Pythium and Rhizoctonia. |
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UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Diseases
R. D. Raabe (emeritus), Environmental Science, Policy, and Management (ESPM),
UC Berkeley
M. E. Grebus, Plant Pathology, UC Riverside
C. A. Wilen, UC IPM Program, UC Cooperative Extension, San Diego Co.
A. H. McCain (emeritus), Environmental Science, Policy, and Management (ESPM),
UC Berkeley
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