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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 Plum 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.

Ceasar

Active

Solanum tuberosum L. · Potato

IT
3 records

Corallo

Terminated

Capsicum annuum L. · Bell pepper

IT
2 records

BROKFOREST

Active

hybrids between Prunus davidiana and Prunus persica

ES
2 records

CARRIZO

Active

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

ES
2 records

Brasla

Active

Solanum tuberosum L. · Potato

LV
3 records

Boston

Terminated

Cucumis sativus L. · Cucumber

NL
2 records

Brinjak

Active

Solanum tuberosum L. · Potato

HR
2 records

Bell Tower

Terminated

Capsicum annuum L. · Bell pepper

NL
2 records

Boglárka

Active

Solanum tuberosum L. · Potato

HU
2 records

ABT 205

Terminated

Medicago sativa L. · Alfalfa

EE
2 records

Amicii

Protection expired

Solanum tuberosum L. · Potato

RO
2 records

Amelia

Active

Fragaria x ananassa Duchesne ex Rozier · Garden strawberry

NL
6 records

Ascanio

Active

Solanum lycopersicum L. · Tomato

HU
2 records

B 490

Active

Malus domestica (Suckow) Borkh. · Apple

NL
2 records

B 491

Active

Malus domestica (Suckow) Borkh. · Apple

NL
2 records

Astral N

Protection expired

Solanum tuberosum L. · Potato

RO
2 records

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