Download What Would I Do If I Was A Potato Grower

Bacterial Ring Rot….a Wide Spread
Problem…..
What Does it Look Like & What to do
When Found
Philip B Hamm
Plant Pathologist
Oregon State University
Hermiston Agricultural Research &
Extension Center
Why Have This “Conversation”?
1. Because we can not afford to concentrate on
other issues and forget this very serious
pathogen
2. Most have never seen this problem or it has
been a long time since last seen
3. There was a number of farms that had this
disease last year….at a large cost
4. The problem just doesn’t go away….it will
likely be an issue in 2014 if proper practices
are not followed
Specific Areas to be Covered
• Bacterial Ring Rot (BRR)
– What is Bacterial Ring Rot and why it is important
– Symptoms
• Above ground
• Below ground
– Where does it come from…how does the disease
happen
– Management
What is Bacterial Ring Rot?
• A bacterial problem, seedborne, caused by Clavibacter
michiganensis subsp. sepedonicus
• Given the nature of bacteria, easily spread, particularly at seed
cutting
• Damage/loss is caused by the
rot that occurs in the field,
in storage, and issues during
processing
• This disease clearly is one, if
not “THE” disease in potato
not to have! EVER!
What is Bacterial Ring Rot….continued
• Infection
– Wounds are necessary for ring rot bacteria to enter
potatoes; readily transmitted during seed cutting
– Handling (moving, shipping etc.) are all ways to wound
tubers and provide a way for the bacteria to enter
– Chewing insects, such as Colorado potato beetle and
flea beetles have been reported to transmit the bacteria
– BRR bacteria can survive in volunteer potato plants so
contamination could occur when “volunteer” potatoes
are mixed at harvest with the planted crop
Why is this disease important?
• Obvious…yield reduction (rot in the field and
rot problems in storage)
• Processor contracts have little or zero
tolerance for this disease….fields were
rejected this past year due to this disease
– Lightly symptomatic or non symptomatic but
infected tubers result in discolored fries or chips
Symptoms
Foliar Symptoms of BRR
External Tuber Symptoms of BRR
Internal Tuber Symptoms of BRR
Name comes from
This symptom
Where does it come from…how
does the disease happen?
Where does it come from…how does that
happen?
• Essentially poor sanitation
– This is the reason why recommendations were
originally made about cleaning and disinfecting
equipment and facilities between lots and
between years
– Generally potatoes are resilient…In other words
they overcome many negative things we do to
them….but BRR is an exception…this one will get
the grower!!!
Where does it come from…how does
that happen
• Seldom seen by most potato growers in their
career…so the problem is not recognized
• Progressive
– Seed lot gets contaminated in one of the years of seed
lot expansion due to poor sanitation practices
• Infection starts out at very low incidence
• Next generation or even two may have little or no symptomatic
plants
• When the Gen 3 seed is cut by the commercial grower the level
of infection could easily become 1-5%
• Therefore the older the generation (3, 4, 5) the greater the
chance of BRR at significant levels
• The earlier the generation the seed lot is infected the higher
the potential incidence of infection
Management….
whether seed grower or
commercial grower
Management
• The use of certified disease free seed
– Adequately tested/observed and confirmed
“Zero” for this specific disease
• 4400 tubers from each “average” size seed lot, twice
that many if a large seed lot. 1100 tubers minimum for
small lots.
• Tested with PCR using proscribed methods
• Winter grow out field readings also
helpful but do not take the place of
laboratory testing
Management ..Continued
• The maintenance of a very strict and
comprehensive sanitation program…why?
– The bacteria are capable of surviving 2-5 yrs. in dried slime
on the surfaces of crates, bins, burlap sacks, truck beds,
harvesting and grading equipment.
• Clean equipment between seed lots and between years.
– Temperatures below freezing does not eliminate the
bacteria
– Bacteria do not survive in soil but can
survive in volunteer potatoes…control
volunteers!
Management Continued….
Sanitation of Facilities
• Remove all trash (tubers, vines, soil, broken boxes
and old bags, etc.) from the storage, and properly
discard or burn
• Once cleaned, storage bins and walls and floors
should be thoroughly washed with a highpressure washer using hot soapy water, and then
rinsed well
• After washing and rinsing, a disinfectant must be
applied according to label directions
Management Continued….
Sanitation during seed cutting
• The bacteria can be spread by knives during seed
cutting (one infected tuber can spread the bacteria
to the next 20-100 seed pieces
• All containers, tools, and implements (including knives,
cutters, belts, graders, truck beds, planters, etc.) should
be cleaned, and then sanitized
• Clean and disinfect cutting equipment, preferably 3x per
day, and always between lots
• Open-cell sponge rollers that absorb water
(and bacteria) are best avoided--use water
impermeable (closed-cell) rollers instead
Management Continued…
Sanitation During Planting
• Disinfect trucks and planter(s) between each
seed lot
• Don’t use a pick planter
• Do not plant in a field with
BRR last year
• Do not plant in a field with
volunteers with a history of
this disease
What to do or not do if found in the
field
• Be watchful…again confirm by lab testing
• Not all tubers are infected and/or will exhibit
symptoms if a hill is dug
• No pesticide can be applied that will reduce
infection
• Letting infected tubers rot before harvest may
limit the number of tubers at harvest that are
infected
• Placing tubers in storage with BRR is a potential
time bomb given the chance of hot spots in the
pile developing from infected potatoes
Summary
• BRR is a very significant potato disease problem
• The presence of this pathogen in potato production is cyclic
– 10-12 yr cycle; 4-5 yr impact per cycle
– Likely due to the failure to maintain good
sanitation practices
– Also likely due to inadequate testing methods
to confirm BRR
• For management….Maintain/Increase sanitation efforts
• For management…New testing technology and increased
sample size could have a significant impact on confirming this
disease in a seed lot
• Don’t plant seed unless it has been correctly tested for BRR
Questions??
• Special thanks to Brenda Schroeder and Debra Inglis for
supplying some of the slides used today.