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.

Sources10

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

Barley 509 Sugar beet 487 Tomato 250 Perennial ryegrass 167 Cucumber 160 Garden strawberry 123 Bread wheat 105 Rapeseed 80 Tall fescue 79 Kentucky bluegrass 76 Maize 66 Carrot 59

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.

Double Pink

Active

Hydrangea macrophylla (Thunb.) Ser. · Bigleaf hydrangea

Information regarding the breeder received in the contribution to CPVO :Ryoji Irie

1 record

Blue Deckle

Active

Blue Billow

Active

Hydrangea serrata (Thunb.) Ser. var. serrata · Tea-of-heaven

Information regarding the breeder received in the contribution to CPVO :Lighty R. and Bruce H.

1 record

Chantal I

Withdrawn

Cucumis sativus L. · Cucumber

1 record

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Diseases

Powdery mildew 33 570
Fusarium wilt and blight 29 887
Viral mosaic diseases 22 022
Downy mildew 16 384
Rust 14 859
Verticillium wilt 12 175
Scab 12 064
Grey mold 7 316

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Text source

This summary is compiled from the publications listed in the sources and verified by an editor. It contains no legally significant information; it provides agronomic context for registry data rather than the registry data itself.