Agriculture Reference
In-Depth Information
of infected tubers prior to storage and storage
management using forced air ventilation, and
controlled temperature and humidity feedback
systems (Knowles and Plissey, 2007). There is a
shortage of postharvest fungicides or effective
disinfectant products to control these pathogens
completely (Olsen et al ., 2003; Slininger et  al .,
2007; Olsen, 2010). The few compounds avail-
able for potato tuber treatment in storage in-
clude chlorine-based disinfectants such as so-
dium hypochlorite, calcium hypochlorite, and
chlorine dioxide, and mixtures of hydrogen peroxide
and peroxyacetic acid (Wharton et al ., 2007a).
Hydrogen peroxide (H 2 O 2 ; Storox TM , hydrogen di-
oxide 27%; BioSafe Systems, Glastonbury, Con-
necticut, USA) is a broad-spectrum disinfectant
that is able to provide immediate control of stor-
age pathogens (Olsen and Miller, 2005). Hydro-
gen peroxide is environmentally friendly, with its
activities based on the oxidation of fungi and
bacteria, and has been reported to control silver
scurf (Afek et al ., 2001), pink rot (Al-Mughrabi,
2006), and early blight (Al-Mughrabi, 2005) suc-
cessfully. However, use of disinfectants does not
control storage pathogens completely (Olsen
et  al ., 2003; Miller et al ., 2006), hence other
postharvest products in combination with
proper storage management are recommended
(Powelson and Rowe, 2008).
In recent years, several new biocontrol fun-
gicides based on bacteria, Bacillus subtilis (QST
713; Serenade; AgraQuest, Inc, California) and
Bacillus pumilis (QST 2808; Sonata; AgraQuest,
Inc, California, USA) have been registered for
control of potato pathogens. These products are
used for organic potato production to comple-
ment copper products and have successfully
shown a reduction of foliar late blight disease
development (Stephan et al ., 2005). B. subtilis
produces three groups of lipopeptides that work
together to stop spores of plant pathogens from
germinating, disrupt germ tube and mycelial
growth, and inhibit attachment of the plant
pathogen to the leaf surface (Marrone, 2002).
Another product registered for postharvest use is
Bio-Save 10LP ( Pseudomonas syringae : ESC-10),
which has been reported to reduce Fusarium dry
rot and silver scurf when applied to tubers prior
to storage (Hopkins and Hirnyck, 2008). B. subtilis
effectively controlled postharvest diseases of po-
tatoes in combination with field-applied biofun-
gicides and fungicides (Gachango et al ., 2012c).
Phosphorous acid (Phostrol mono- and di-
basic sodium, potassium and ammonium salts
of phosphorous acid; Nufarm Americas, Inc,
AGT-Division, Burr Ridge, Illinois, USA) was re-
cently registered for postharvest use in potato
production (Powelson and Rowe, 2008). The US
Environmental Protection Agency (US-EPA)
considers it to be a systemic fungicide but not a
biochemical ( http://www.epa.gov/opp00001/
chem_search/reg_actions/registration/fs_PC-
076416_1-Oct-98.pdf ). The direct effects of
phosphorous acid include inhibition of mycelial
growth and inhibition of particular metabolic
processes, and the indirect effects include stimu-
lation of the natural defense responses of the
plant (Guest and Bompeix, 1990). Phosphorous acid
has been reported to control effectively tuber late
blight and pink rot in storage (Inglis et al ., 2004;
Johnson et al ., 2004; Gachango et al ., 2012b).
Control of dry rot in storage has been
achieved primarily through reducing tuber
bruising, providing conditions for rapid wound
healing (Secor and Johnson, 2008), and apply-
ing TBZ (Mertect 340- F, Syngenta, Greensboro,
North Carolina, USA), a benzimidazole fungi-
cide, as tubers are loaded into storage (Hide et al .,
1992). However, F. sambucinum resistant to TBZ
and other benzimidazole fungicides was dis-
covered in Europe in 1973 (Hide et al ., 1992)
and in the USA in 1992 (Desjardins, 1995),
leading to reduced effectiveness in controlling
dry rot (Staub, 1991). To counteract this loss,
registration of other chemistries is imperative,
and recently Stadium ® , a three-way mixture of
fungicides from three different FRAC groups
(azoxystrobin (11), fludioxonil (12), and difeno-
conazole (3)) was registered in the USA by Syn-
genta Crop Protection for control of dry rot and
silver scurf (Kirk et al ., 2013).
11.4
Future Prospects
Climate change
The viability of potato production is affected by
spatial and temporal variability in soils and wea-
ther and the availability of water resources where
supplementary irrigation is required (Savary et al .,
2011; Daccache et al ., 2012). Soil characteristics,
markets, and agroclimatic conditions influence
 
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