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Botrytis Primer

General Information Summary
Pathogens & Hosts Taxonomy Characteristics Disease Types Management Graphics References


Andrew K. Gonsalves, Educational Specialist

Stephen A. Ferreira, Extension Plant Pathologist

Department of Plant Pathology, College of Tropical Agriculture and Human Resources

University of Hawaii at Manoa


Over four Botrytis species have been reported to occur in Hawaii (Raabe, et al., 1981). The following is a list of the reported pathogens from this genus (Botrytis) and the hosts they infect. The list is organized by the scientific name of the pathogen species (CAPITAL LETTERS), followed by the various susceptible plant hosts. Words in blue indicate what symptom or disease a given pathogen causes on the listed hosts.


Blossom Blight:

Dendrobium sp.

easter lily (Lilium longiflorum)

Limonium sp.

macadamia (Macadamia integrifolia)

mango (Mangifera indica)

petunia (Petunia hybrida)

Plumeria acuminata

tuberose (Polianthes tuberosa)

azalea (Rhododendron indicum)

tea rose (Rosa odorata)

gloxinia (Sinningia speciosa)

Vanda sp.

pansy (Viola tricolor)

Botrytis Blight:

Cymbidium sp.

Crown and Head Rot:

head lettuce (Lactuca sativa var. capitata)

Dark Necrotic Flecks on Flowers (isolated from):

Dendrobium sp.

Flower Blight:

pincushion protea (Leucospermum cordifolium)

Fruit Rot:

strawberry (Fragaria chiloensis var. ananasa)

Gray Mold:

carnation (Dianthus caryophyllus)

Gray Mold Blight:

big-leaf periwinkle (Vinca major)

Gray Mold Rot:

wine grape (Vitis vinifera)

Leaf Blight:

florist's chrysanthemum (Chrysanthemum morifolium)

hydrangea (Hydrangea macrophylla)

Pelargonium sp.

Petal Blight:

gardenia (Gardenia jasminoides)

Shoot and Flower Blight:

Protea nutans

Soft Rot:

African violet (Saintpaulia ionantha)


poinsettia (Euphorbia pulcherrima)


Blossom Blight:

bird-of-paradise (Strelitzia reginae)

Leaf Blight:

head lettuce (Lactuca sativa var. capitata)


Dendrobium nobile

carnation (Dianthus caryophyllus)

Passiflora sp.

Vanda sp.


Leaf Blight:

onion (Allium cepa)



Tulipa sp.


KINGDOM: Mycetae (fungi)

DIVISION: Eumycota

SUBDIVISION: Deuteromycotina (The imperfect fungi)

CLASS: Hyphomycetes

ORDER: Hyphales (Moniliales)

FAMILY: Moniliaceae



Botrytis spp. produce gray mycelium. Their condiophores are long and branched with rounded apical cells bearing clusters of colorless or gray, one-celled, ovoid condia (Agrios, 1988). This structure resembles a grapelike cluster (Agrios, 1988).


Conidia are easily released in humid weather and are disseminated by wind (Agrios, 1988). This fungus overwinters in the soil either as mycelium on decaying plant debris or as sclerotia (Agrios, 1988). At this stage, the fungus can be spread by the movement of contaminated soil and plant debris. Cool (18-23 C) and damp weather are ideal for growth, sporulation, spore release and germination, and infection (Agrios, 1988). Conidia can germinate and penetrate tissue primarily through wounds. Conidia seldom penetrate tissue directly. However, once the spore germinates and the mycelium is actively growing, the fungus can penetrate the tissue of old flower petals, dying foliage, and dead bulb scales (Agrios, 1988).


Botrytis diseases are very common and widely distributed on vegetables, ornamentals, fruits, and field crops throughout the world (Agrios, 1988). They commonly appear as blossom blights and fruit rots. Other diseases caused by this fungus are damping off, stem cankers and rots, leaf spots, and tuber, corm, bulb, and root rots (Agrios, 1988). The most serious diseases caused by this fungus are: gray mold of strawberry, gray mold rot of vegetables (i.e., artichoke, bean, beet, cabbage, carrot, cucumber, eggplant), tip-end rot (i.e., bananas, lettuce, pepper, squash, tomato), onion blast and neck rot, calyx end rot of apples, blossom and twig blight of blueberries, blight or gray mold of ornamentals (i.e., African violet, begonia, cyclamen, chrysanthemum, dahlia, geranium, hyacinth, lily, peony, rose, snapdragon, stock, tulip), bulb rot of amaryllis, corm rot, leaf spot, and stem rot of gladiolus (Agrios, 1988). As a postharvest disease, this fungus can cause gray mold of many fruits and vegetables (Agrios, 1988).


Removal of contaminated tissue from the field and from storage rooms can help to manage Botrytis infection. Proper aeration to allow quick drying of plants and plant products, and other means of keeping greenhouses and storage rooms at low humdity levels can also aid in managing this fungus (Agrios, 1988).

Biological control of gray mold of apple was successful using a spore suspension of the antagonistic fungus Trchoderma harzianum to spray on flowers (Agrios, 1988). However, as of 1988, this approach is not used in practice.

Chemical control has been only partially successful (Agrios, 1988). A list of chemical controls for various Botrytis diseases follows (Agrios, 1988):

Botrytis rot of:

a. lettuce: dichloran or zineb sprays;

b. onion and tomato: difolatan, dyrene, maneb-zinc, maneb, and chloraothalonil.

Fruit rots (i.e., gray mold) of:

a. strawberry: sprays or dusts with captan, thiram, or benomyl.

Other contact fungicides being tested on a wide variety of crops (as of 1988):

a. iprodione

b. vinclozolin.

To reduce the appearance and the establishment of resistant Botrytis strains, different fungicides and fungicide combinations are recommended (Agrios, 1988).


Agrios, G.N. 1988. Plant Pathology, 3rd edition. Academic Press, Inc: San Diego. 803 pp.

Alexopoulos, C.J. and C.W. Mims. 1979. Introductory Mycology, 3rd edition. John Wiley and Sons, Inc.: New York. 632 pp.

Farr, , D.F., G.F. Bills, G.P. Chamuris, and A.Y. Rossman. 1989. Fungi on Plants and Plant Products in the United States. APS PRESS: St. Paul, Minnesota. 1252 pp.

Raabe, Robert D., Ibra L. Conners, and Albert P. Martinez. 1981. Checklist of Plant Diseases in Hawaii. Hawaii Institute of Agriculture and Human Resources, College of Tropical Agriculture and Human Resources, University of Hawaii (Information Text Series 022).

Streets, R.B. 1982. The Diagnosis of Plant Diseases: a field and laboratory manual emphasizing the most practical methods for rapid identification. The University of Arizona Press: Tucson, Arizona.



JUNE 1994



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