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.

Rustler

Withdrawn

Festuca arundinacea Schreb. · Tall fescue

Grassland Oregon

1 record

Rouge mammouth

Terminated

Beta vulgaris Fodder Beet Group · Mangelwurzel

Domaine Public (FR)

1 record

RODYNA

Active

Beta vulgaris Garden Beet Group · Garden beet

Sakata Vegetabels Europe, F

1 record

Salviai

Terminated

Ribes nigrum L. · Blackcurrant

Lietuvos agrarinių ir miškų mokslų centro filialas Sodininkystės ir daržininkystės institutas

1 record

Royal Dynasty

Withdrawn

Brassica oleracea L. (White Cabbage Group) · White cabbage

Seminis Vegetable Seeds

1 record

Sacramento

Withdrawn

Triticum aestivum L. · Bread wheat

RAGT 2n, FR

1 record

Rigel

Application submitted

Arachis hypogaea L. · Peanut

Atlas Tohum Ziraat Ltd Sti

1 record

RM 35

Terminated

Sorghum bicolor (L.) Moench subsp. bicolor · Sorghum

Sud Cereales (FR)

1 record

Rhonda F1

Active

Beta vulgaris Garden Beet Group · Garden beet

Ger Bimsdeboer

1 record

Remiz Niwa

Application submitted

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

Niwa Hodowla Roślin Jagodowych sp. z o.o.

2 records

RGT Topallur

Active

Triticum durum Desf. · Durum wheat

RAGT 2n, FR

1 record

Ritali

Terminated

Saintpaulia H. Wendl. · African violet

HOLTKAMP JUN| Hermann Holtkamp jun. in Fa. Hermann Holtkamp KG / HOLTKAMP REINHOLD| Reinhold Holtkamp / HOLTKAMP RUDOLF| Rudolf Holtkamp

1 record

Relexma

Application submitted

Brassica oleracea L. (Red Cabbage Group) · Red cabbage

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

1 record

RH08025

Withdrawn

Zea mays L. · Maize

RAGT 2N S.A.S

1 record

R400MR

Active

Zea mays L. subsp. mays (Popcorn Group) · Popcorn

CROOKHAM COMPANY

1 record

R606

Active

Zea mays L. subsp. mays (Popcorn Group) · Popcorn

CROOKHAM COMPANY

2 records

Red Bull

Active

Beta vulgaris Garden Beet Group · Garden beet

Mario Martinelli

2 records

PSG711

Withdrawn

Poa pratensis L. · Kentucky bluegrass

PICKSEED

1 record

Red Rock

Withdrawn

Echinodorus L.C. Rich ex Engelm. · Amazon sword

KALIEBE TOMAS| Tomas Kaliebe (Gartenbau)

1 record

PST-2LGS

Withdrawn

Lolium perenne L. · Perennial ryegrass

PURE SEED TESTING

1 record

Progress F1

Terminated

Solanum lycopersicum L. · Tomato

Hari Besels

1 record

PSG5RM

Application submitted

Festuca rubra L. · Red fescue

PICKSEED

1 record

Premier

Terminated

Cucumis sativus L. · Cucumber

Asgrow Seed Company (US)

1 record

Quimby

Application submitted

Cucumis sativus L. · Cucumber

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

2 records

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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.