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Gray Mold

Botrytis cinerea

78 host plants

Last updated

Data Coverage 3 of 6 dimensions
Causal Agent
Host Plants
Symptoms
Management
GDD Threshold
Regional Notes

Gray mold makes itself known when current-season shoots on conifers and susceptible ornamentals curl, twist, wither, and turn brown, often with a distinctive fuzzy gray fungal growth visible in moist conditions. The infection may start in lower foliage and move upward, killing needles and woody portions of the shoot. Unlike frost damage, which causes similar wilting, gray mold leaves a telltale gray fungal coating over infected areas when humidity is high, making diagnosis straightforward. This disease affects a wide range of plants from Douglas fir to kiwi, and establishes wherever humidity, moisture on foliage, and dead or wounded plant parts converge.

The reason gray mold thrives in cool, humid climates is the naturally humid springs and falls, and controlling it hinges entirely on managing moisture and air movement rather than fungicides. Remove all dead and dying plant parts (especially flowers and fallen debris) from your greenhouse or growing area, space plants generously to ensure air flows freely around foliage, and maintain humidity below 90% through venting and heating if necessary. Avoid wetting foliage during watering, particularly in evening hours when moisture lingers, and clean and sanitize growing areas before each production cycle to eliminate fungal spores overwintering in crop debris.

Quick Reference

Causal Agent
Botrytis cinerea
Host Plants
78

Management

Cultural Controls

  • An integrated strategy combining environmental management, cultural practices, and fungicides will most effectively manage this disease.
  • Thoroughly clean and sanitize the greenhouse before production.
  • Remove all dead and dying plant parts (particularly blossoms) on and around plants and take them out of the greenhouse.
  • Many growers use closed containers to minimize the amount of conidia.
  • Maintain a steady, relatively dry environment by keeping greenhouse humidity below 90%, increasing spacing between plants for good air circulation, and taking care not to splash water on foliage during watering.
  • Heating the greenhouse at night (especially for zero or negative DIF) or venting around sunset may be necessary.

Host Plants (78)

Actinidia kolomikta Kolomikta Actinidia Kolomikta Kiwi Arbutus unedo Strawberry Tree, Killarney Strawberry Tree, Madroño Ceratonia siliqua Carob St. John's Bread Locust, Bean Chrysanthemum coccineum Chrysanthemum Cynara scolymus Artichoke Daphne genkwa Lilac Daphne Dermatophyllum secundiflorum Mescal Bean Texas Mountain Laurel, Frijolito Dianthus Sweet William Euphorbia Wood Spurge Fragaria chiloensis Beach Strawberry Sand Strawberry, Chilean Strawberry Pinus albicaulis Whitebark Pine, Scrub Pine, White Pine Pinus aristata Bristlecone Pine, Rocky Mountain Bristlecone Interior Bristlecone Pinus attenuata Knobcone Pine Pinus banksiana Jack Pine, Scrub Pine, Banksian Pine, Hudson Bay Pine Pinus bungeana Lacebark Pine, Whitebark Pine, Baipi Song Pinus canariensis Canary Island Pine Pinus cembra Swiss Stone Pine Pinus contorta Lodgepole Pine Pinus contorta var. contorta Shore Pine Pinus contorta var. latifolia Rocky Mountain Lodgepole Pine Pinus coulteri Coulter Pine, Bigcone Pine Pinus densiflora Japanese Red Pine Pinus edulis Pinyon Pine, Piñón Pine, Two-needle Pinyon Colorado Pinyon Pinus elliottii Slash Pine, Swamp Pine Pinus flexilis Limber Pine, Rocky Mountain White Pine Pinus halepensis Aleppo Pine, Jerusalem Pine Pinus heldreichii Bosnian Pine, Snakeskin Pine Pinus jeffreyi Jeffrey Pine, Western Yellow Pine, Bull Pine Pinus kwangtungensis Kwangtung Pine, Guangdong Pine Pinus lambertiana Sugar Pine Pinus leucodermis Bosnian Pine Pinus monophylla Singleleaf Pinon Pine, One-leaved Pine Pinus monticola Western White Pine Pinus mugo Mugo Pine Pinus mugo var. pumilio Mugo pine, Dwarf Mugo pine Pinus nigra Austrian Pine Pinus parviflora Japanese White Pine Pinus parvifola Pinus parvifola Pinus pinaster Maritime Pine, Cluster Pine, Turpentine Pine Pinus pinea Italian Stone Pine, Umbrella Pine Pinus ponderosa Ponderosa Pine, Western Yellow Pine Pinus pumila Japanese Stone Pine, Dwarf Siberian Pine Pinus radiata Monterey Pine Pinus resinosa Red Pine Pinus sabiniana Gray Pine, Foothill Pine Pinus strobiformis Southwestern White Pine, Mexican White Pine, Chihuahua White Pine Pinus strobus Eastern White Pine Pinus sylvestris Scots Pine, Scotch Pine Pinus thunbergii Japanese Black Pine Pinus virginiana Virginia Pine, Scrub Pine, Jersey Pine Pinus wallichiana Himalayan Pine, Bhutan Pine Pinus yunnanensis Yunnan Pine Pseudotsuga macrocarpa Bigcone Douglas-fir Pseudotsuga menziesii Douglas-fir Pseudotsuga menziesii var. glauca Rocky Mountain Douglas-fir Blue Douglas-fir Inland Douglas-fir Colorado Douglas-fir Pseudotsuga wilsoniana Taiwan Douglas-fir Rheum rhabarbarum Rhubarb Solanum aviculare Kangaroo Apple Sophora secundiflora Mescal Bean Texas Mountain Laurel, Frijolito Syringa chinensis Chinese Lilac Rouen Lilac Syringa hyacinthiflora Early Flowering Lilac, Early Hybrid Lilac Syringa josikaea Hungarian Lilac Syringa laciniata Cutleaf Lilac Syringa meyeri Syringa meyeri Syringa microphylla Syringa microphylla Syringa patula Syringa patula Syringa pekinensis Peking Lilac Chinese Tree, Lilac Syringa prestoniae Preston Lilac, Canadian Lilac Syringa reticulata Japanese Tree Lilac, Giant Tree Lilac Syringa vulgaris Common Lilac Tsuga canadensis Canadian Hemlock, Eastern Hemlock Tsuga canadensis var. pendula Weeping Hemlock Tsuga diversifolia Northern Japanese Hemlock Tsuga heterophylla Western Hemlock Tsuga mertensiana Mountain Hemlock Viola Hookedspur Violet Waldsteinia fragarioides Barren Strawberry Zantedeschia White Calla Lily