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Diseases

Late blight

Phytophthora infestans

Late blight is a dangerous disease of solanaceous crops caused by an oomycete, which manifests as the appearance of spots on leaves, stems, and tubers. The development of the disease is triggered by high humidity and moderate temperatures, which can lead to significant crop losses.

Mentioned in descriptions 6 798 varieties reference book.

Affected plants develop dirty-brown spots, often accompanied by a whitish mold on the underside of the leaf, while elongated dark-brown spots appear on the stems. Tubers show hard, sunken brown spots, and the internal tissue exhibits a characteristic rust-brown discoloration upon cutting.

Epiphytotics develop under conditions of high air humidity around 90% and alternating warm days with cool nights. The presence of free moisture, such as dew or fog, is a critical factor for rapid spore germination, which allows the infection to spread across the field in 10–15 days.

In breeding, a distinction is made between specific vertical resistance, controlled by R-genes, and field horizontal resistance, which is considered more reliable due to its polygenic nature and ability to slow down pathogen development. Varieties are evaluated using a 9-point scale; however, the resistance level of the foliage does not always coincide with that of the tubers, requiring comprehensive analysis during variety testing.

Sources10

Breakdown by crop

Potato late blight 1 396 Tomato Late Blight 273 Phytophthora root rot of strawberry 99 Phytophthora Root and Stem Rot of Soybean 61 Phytophthora Root Rot of Alfalfa 41 Phytophthora blight of pepper 41 Apple Phytophthora Rot 24 Phytophthora Root Rot of Raspberry 21 Apple Phytophthora Rot 20 Tomato Late Blight 17 Citrus Phytophthora 17 Plum Phytophthora root rot 15 Phytophthora blight — hybrids between Citrus x aurantium L. x Citrus trifoliata L. 13 Strawberry Phytophthora root rot 13 Phytophthora Root Rot of Blueberry 11 Phytophthora root rot of sweet chestnut 9 Phytophthora blight — Leek 7 Phytophthora root rot of sour cherry 6 Phytophthora root rot of paradise apple 6 Avocado Phytophthora Root Rot 6 Peach Phytophthora Root Rot 5 Phytophthora root rot of Vaccinium 5 Late Blight of Eggplant 4 Phytophthora root rot of Prunus amygdalus x Prunus persica 4

Found in these crops

Potato 1 394 Tomato 276 Garden strawberry 124 Soybean 64 Bell pepper 56 Alfalfa 41 Red raspberry 34 Apple 26 Sweet chestnut 25 Citrus 22 Apple 19 Hybrids between Citrus x aurantium L. x Citrus trifoliata L. 16

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.

OVATION

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

Heinz2586

Active

Solanum lycopersicum L. · Tomato

1 record

Fairland

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

Dixie

Active

Vaccinium corymbosum L. · Highbush blueberry

1 record

GF 8/1

Active

Prunus L. · Plum

2 records

ITASCA

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

CARRIZO

Active

Citrus L. · Citrus

2 records

Contesa

Terminated

Solanum melongena L. · Eggplant

1 record

ColUTAD

Active

Castanea sativa Mill. · Sweet chestnut

1 record

CITRUMELO SWINGLE

Active

Hybrids between Citrus x aurantium L. x Citrus trifoliata L.

1 record

LATESTAR

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

Frumoasa

Terminated

Solanum tuberosum L. · Potato

1 record

GLOOSCAP

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

CATSKILL

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

Auchincruive

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

Hummi-Ferma 2000

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

1 record

Himpo Top

Active

Rubus idaeus L. · Red raspberry

1 record

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