Taxonomy

Resistance

Tomato disease resistance codes are useful when it comes time to select tomato varieties for your garden and growing region.
Think about your previous season- Did you struggle with fungal issues? Was there an entire bed affected by a virus?
Many types of diseases can carry over to the next season in your soil and sometimes even on your saved seed.
You may want to consider growing some resistant varieties or using them as rootstock for your favorite heirlooms
that need just a little bit of help defending themselves in the throes of the growing season.

In some cases, there are multiple codes listed for different strains of the same disease.
As well, seed companies in different regions of the world may present the same disease code in different ways,
which can be a bit confusing. For continuity, the tomato disease codes listed below are codes that are typically found in official
tomato registers in several countries across the globe.

Bacterial Diseases

BS or (Pst/Pst: 0) – Bacterial Speck (Races 0)
Scientific Name: Pseudomonas syringae

BW – Bacterial Wilt
Scientific Name: Erwinia tracheiphila

Fungal Diseases

A – Anthracnose
Scientific Name: Colletotrichum lagenarium

A / Aal / AS/ ASC – Alternaria Stem Canker
Scientific Name: Alternaria alternata f.sp. lycopersici

BS – Black Speck
Scientific Name: Rhizoctonia ssp

CRR – Corky Root Rot
Scientific Name: Pyrenochaeta lycopersici

EB/AB – Early Blight (Alternaria Blight)
Scientific Name: Alternaria solani

F/FF/FFF or (Fol: 1, 2, 3) – Fusarium Wilt (Races 1, 2 and 3)
Scientific Name: Fusarium oxysporum, Fusarium oxysporum f. sp. lycopersici

FOR – Fusarium Crown and Root Rot
Scientific Name: Fusarium oxysporum f. sp. radicis–lycopersici

GLS – Gray Leaf Spot
Scientific Name: Stemphylium solani

LB – Late Blight
Scientific Name: Phytophthora infestans

LM or (Ff: A-E) – Leaf Mold (Races A, B, C, D, and E)
Scientific Name: Passalora fulva, Cladosporium fulvum, Fulvia fulva

PM or (On) – Powdery Mildew
Scientific Name: Oidium neolycopersici, Oidium lycopersicum, Leveillula taurica, Oidium lucopersici

St or GLS – Stemphylium Gray Spot Leaf (Gray Leaf Spot)
Scientific Name: Stemphylium solani, S. lycopersici, S. floridanum, and S. botryosum

Viral Diseases

T or TMV – Tobacco Mosaic Virus
Disease Name: Scientific Name: Tobacco mosaic virus, positive-sense single-stranded RNA virus (Tobamovirus)

ToANV – Tomato Apex Necrosis Virus
Scientific Name: Tomato Apex Necrosis Virus

ToMV or (ToMV:0-2) – Tomato Mosaic Virus (Races 0, 1, and 2)
Scientific Name: Tobamovirus

TSWV or SWV – Tomato Spotted Wilt Virus
Scientific Name: Tomato spotted wilt virus (genus Tospovirus; family Bunyaviridae)

TYLCV – Tomato Yellow Leaf Curl Virus
Scientific Name: Begomovirusa (Tomato yellow leaf curl virus)

V / Va / Vd – Verticillium Wilt (Races Va: 1 or Vd: 1)
Scientific Name: Verticillium dahlia, Verticillium albo–atrum

Parasitic Diseases

N or (Ma/Mi/Mj) – Root-Knot Nematode
Scientific Name: Meloidogyne spp., Meloidogyne arenaria, M. incognita, M. javanica

Two additional codes that are sometimes found on seed packages characterize
the level of resistance of a particular variety to a given disease:

HR= High Resistance
IR= Intermediate Resistance