McLARLOU
ActivePhotinia x fraseri Dress · Fraser's photinia
McWhinnie Louise / McLaren Robert / McIsaac Debbie
Diseases
Leaf spot diseases
Leaf spot diseases are a group of fungal, bacterial, or viral disorders manifesting as tissue necrosis in the form of spots of various shapes and colors. Pathogen development leads to a reduction in photosynthetic leaf area, tissue deformation, and significant yield losses.
Mentioned in descriptions 15 926 varieties reference book.
Leaf spot diseases represent a collective group of conditions caused by fungi, bacteria, or viruses. The primary diagnostic symptom is the formation of spots of various colors—brown, yellow, black, or gray—on the leaf blades, ranging from small dots to extensive necrotic lesions with or without margins. Infection often originates in the lower leaf canopy and, if allowed to develop, leads to premature defoliation and overall plant weakening.
Disease progression depends on a combination of favorable meteorological factors, such as moderately warm temperatures and high humidity, as well as the agrotechnical background. Improper crop rotation and the retention of crop residues in fields contribute to the accumulation of inoculum and intensive infection of crops in subsequent seasons. The severity of disease manifestation correlates directly with pathogen aggressiveness and the degree of cultivar susceptibility, which can lead to a 20–30% or greater reduction in crop productivity.
Cultivar resistance to leaf spots is a genetically determined ability to maintain productivity under disease pressure. It can be specific, targeting particular pathogen races, or non-specific polygenic, providing complex protection. Resistance mechanisms include physical barriers, such as waxy coatings, and biochemical responses. During variety testing, resistance is evaluated under natural and artificial inoculation conditions using scoring scales to record the degree of necrosis and pathogen development.
Breakdown by crop
Rose leaf spots
789
Tomato Leaf Spots
563
Barley Leaf Spot Diseases
541
Pepper Leaf Spots
277
Cucumber leaf spots
244
Leaf blotch — soft wheat
239
Leaf spots — Perennial ryegrass
181
Leaf spots — garden strawberry
141
Bean leaf spots
139
Leaf spots — tall fescue
125
Potato early blight
123
Peach Leaf Spots
120
Leaf spots of summer squash
107
Leaf Spot — Kentucky Bluegrass
105
Apple Leaf Spot
95
Maize leaf spots
82
Melon Leaf Spot
74
Olive leaf spot
71
Leaf spots — Creeping bentgrass
53
Carrot leaf blights
48
Leaf spots of red fescue
43
Maize leaf spots
35
Plum leaf spots
34
Triticale leaf spots
32
Found in these crops
Varieties that feature this in their description
Selection based on the description text, not official resistance ratings: such data is not available in registers. Mention indicates that the trait is discussed in the variety's sources; see the variety's profile for details on what is specifically stated.
Marietta
ActiveVeronica longifolia L. · Garden speedwell
Ruud Klein
Kolmawhi
ActiveHypericum x inodorum Mill. · Tall tutsan
Jan de Jong
Lindsey Ann
ActiveHydrangea macrophylla (Thunb.) Ser. · Bigleaf hydrangea
John David Bakale Jr.
Low Down
ActiveHelianthus salicifolius A. Dietr. · Willow-leaf Sunflower
Keith R.W. Hammett
Kerbelbut
ActivePrimula vulgaris Huds. · Primrose
Priscilla Grace Kerley, David William Kerley
Kui Nuku
ActiveHibiscus coccineus x Hibiscus moscheutos L.
Zwetzig Gretchen
Lystig
ActiveFestuca rubra L. · Red fescue
Graminor AS, N-2322 Ridabu
Jazzberry Jam
ActiveHibiscus L. · Hibiscus
Walters Gardens Inc
Le Bois Marquis
ActiveViburnum L. · Viburnum
MAURICE LAURENT
Kopper King
ActiveHibiscus L. · Hibiscus
Fleming, David W|8101 S. 14.sup.th St., Lincoln, NE 68512 / Fleming, James R|8101 S. 14.sup.th St., Lincoln, NE 68512
Iver
ActiveHordeum vulgare L. · Barley
Graminor AS, N-2322 Ridabu
Happy Trails
Application submittedTiarella L. · Foamflower
Janet N. Egger
Haeumanarc
ActiveSalvia x sylvestris L. · Wood sage
Häussermann, Martin
Jethro Tull
ActiveCoreopsis auriculata x Coreopsis lanceolata
Saul Robert Mark|Atlanta, GA, US
EPB 12
ActiveHelleborus x hybridus hort. ex Voss · Lenten rose
RODNEY DAVEY|LYNDA WINDSOR
Frenzy
ActiveGaillardia x grandiflora hort. ex Van Houtte · Blanket flower
John A. Dixon
Dioptric
TerminatedHordeum vulgare L. · Barley
Syngenta Participations AG
Flamingo
ActiveEchinacea Moench. · Coneflower
Korlipara Harini
Fantasia
ActiveHibiscus L. · Hibiscus
FLEMING DAVID W.^^^Gretchen Zwetzig
Evipo003
ActiveClematis L. · Clematis
Poulsen Roser A/S^^^EVISON RAYMOND J. LTD
Crown Jewels
ActiveHibiscus L. · Hibiscus
FLEMING DAVID W.^^^Gretchen Zwetzig
ES201
ActiveSesamum indicum L. · Sesame
ORON GAR / NIMROD BARDANOV
Cleopatra
ActivePhlox paniculata L. · Garden phlox
Geerlings-Meyer