Alternaria mali, also called alternaria blotch of apple, is a pathogenic fungus affecting plants. It is prevalent in the southern United States and elsewhere, and damages the leaves of infected apple trees.
| Alternaria mali | |
|---|---|
| |
| Alternaria mali infection | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Dothideomycetes |
| Order: | Pleosporales |
| Family: | Pleosporaceae |
| Genus: | Alternaria |
| Species: | A. mali
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| Binomial name | |
| Alternaria mali Roberts (1914)
| |
Pathogenesis
editAleternaria mali can overwinter as mycelium on dead leaves on the ground, in mechanical injuries in twigs, or in dormant buds.[1] Primary infection occurs about one month after petal fall the following year.[2] The disease is favoured by temperatures between 77 and 86 °F (25–30 °C), and by wet conditions.[1] Infection occurs at optimum temperatures with 5.5 hours of wetting,[2] and an outbreak can become serious within two days of infection. The fungus attacks susceptible cultivars using a chemical toxin.[1] Affected plants exhibit circular spots on the leaves that enlarge as the disease advances. Normally, hyphae cannot adhere to the surface of the host, but under moist conditions light-grey mycelium might be present on the surface.[3] Normally the fungus will not attack fruits except in highly susceptible cultivars;[2] fruit-spotting may occur on the tree or in storage, particularly on fruits with already damaged skin.[3]
Plant defense
editPlants' first lines of defense against A. mali infection are the physical barrier provided by the epidermis on the primary body and the periderm on the secondary body.[4] A. mali can still penetrate the stomates and hydathodes of leaves.[4]
As with most pathogens, Alternaria mali resistance involves a gene-for-gene relationship.[4] Apple trees can recognize invading pathogens and mount a defense.[4] Often, the plant may be able to resist the pathogen, even though it has no genetic resistance to same. Apple trees seem to have a weak defense to A. mali, base on the fact that no survivors if leaves has been infected.[clarification needed]
Control
editAlternaria mali prevention consists of strict quarantine, never importing plants or scions from affected plants and collecting fallen or infected leaves and burning them in winter.[5] Apple cultivars can be ranked in order of increasing resistance as follows: Indo, Red Gold, Raritan, Delicious, Fuji, Golden Delicious, Ralls, Toko, Tsugaru, Mutsu, Jonagold, Jonathan.[2] Chemical control uses fungicides such as iprodione, mancozeb and captan.[6][7] Disease severity is aggravated by severe mite infestation; thus good mite management is an important factor in preventing severe disease development.[1]
References
edit- ^ a b c d Yoder, K.S., & Biggs, A.R. (n.d.). Alternaria Blotch, Alternaria mali Archived 2007-11-12 at the Wayback Machine. Retrieved November 10, 2007
- ^ a b c d Sawamura, K. (1990) Alternaria blotch. In: Compendium of apple and pear diseases (Ed. by Jones, A.L.; Aldwinckle, H.S.), pp. 24–25 American Phytopathological Society, St. Paul, USA.
- ^ a b CABI, & EPPO. (n.d.). Alternaria mali Archived 2008-09-08 at the Wayback Machine. Retrieved November 10, 2007
- ^ a b c d Campbell, N.A.,&Reece, J.B. (n.d.). International edition biology: Plant defense (6th ed.). San Francisco: Benjamin Cummings.
- ^ Bayer cropscience. (2004). (translation: apple alternaria blotch)."Bayer CropScience - China". Archived from the original on 2007-09-12. Retrieved 2007-09-12. (Chinese)
- ^ Lee, C.V.; Kim, K.H. (1986) Cross tolerance of Alternaria mali to various fungicides Archived 2019-05-31 at the Wayback Machine. Korean Journal of Mycology 14, 71–78. (Korean; English abstract available online)
- ^ Osanai, M.; Suzuki, N.; Fukushima, C.; Tanaka, Y. (1987) Reduced sensitivity to captain of Alternaria mali Roberts. Annual Report of the Society of Plant Protection of North Japan 38, 72–73.