Botrytis cinerea

1
Botrytis cinerea
Dealing with Grey rot infection
2
In the Vineyard

• Outline the pathogen
• Review the disease cycle
• Identify Control and management strategies

3
In the Winery

• What are the changes in fruit composition after a
  Botrytis infection?
• What impacts can these changes have on the must
  and wine produced?
• What can we do to minimize the damage?

4
What is Botrytis cinerea?

• Necrotrophic fungus
• Causes damage to its host to obtain nutrients
• Has a variety of hosts and is considered
  Ubiquitious

5
Primary Infection - Sources of Innoculum

• Most inoculum develops from over-wintering in
  vineyard material.
• Inoculum can come from
• Dried fruit structures called mummies.
• Within dormant buds, foliage, or bark.
• Dark, dried, hardened, disc like, structures
  called Sclerotia. (Sclerotia may be present on
  the on the foliage, canes, or mummies)

6
Infection

• Given the right conditions, both mycelium and
  sclerotia will sporolate
• Most spores are asexual conidia.
• Conidia have the ability to germinate between the
  temperatures of 1-30 degrees C.
• They also require free water, or in the absence
  of free water, a relative humidity of greater
  than 93

7
Infection
8
Infection - Continued

• Penetrates the host either by passive or active
  means.
• Passive
• stomatal openings
• wounds
• previous sites of infection by other pathogens
• Active
• enzyme mediated enzymes break down host tissue

9
Disease Cycle
10
Symptoms - Leaves

• V-shaped area of dead brown tissue yellow
  margins.

11
Symptoms - Early Shoot Infection

• Infected shoot turns brown and dries out

12
Infection - Flowering

• Blossoms may dry out or rot.
• At the end of bloom, withered caps and stamens
  may be seen berries may abort.
• Early berry/Bunch infection
• Rachii and pedicels targeted at flowering. This
  can ultimately lead to the inoculation of young
  berries.
• Inoculum can also remain trapped within the
  cluster after bunch closer.

13
Activation of Latent infection

• Why do latent infections activate?
• Reduction of fungi-toxic compounds
• Foliar nitrogen applied post verasion
• Conditions
• Extended periods of humidity

14
Late Season Infection

• Disease cycle can occur every 3-4 days
• Prolonged wet conditions encourage continued
  infection
• At 15 degrees, wetness lasting 15-20 hours may be
  enough for infection to occur.
• Damaged berries an easy target. Disease can
  spread from there.

15
Disease Cycle
16
Noble Rot vs. Gray Rot

• Latent infections become active near the Skin
• Fungal mycelia reach the skin. Hyphae perforate
  it.
• Cells greatly modified and the berry loses its
  ability to regulate hydration.

17
Noble Rot vs. Gray Rot

• Noble Rot
• If the conditions are warm and dry, the berry
  begins to dehydrate.
• High osmotic gradient causes fungal growth to
  cease
• Gray Rot
• If the conditions are wet and humid, the berry
  can not dehydrate.
• Fungal growth continues and spreads.

18
Prevention Strategies?

• Vineyard Sanitation
• Promote injury reduction
• Keep powdery mildew in check
• Bird control
• Insect control if necessary
• Promote an open canopy
• Vigor reduction
• Leaf removal
• Shoot positioning

19
Prevention Strategies?

• Assess varietal susceptibility
• Skin thickness
• Cluster compactness
• Chemical control - Timing, Treatment, Technique
• Spray at the right time
• Use appropriate chemicals
• Ensure adequate spray coverage

20
Chemical Control
21
Chemical Control

• Lance prior to flowering
• Chemical spray 80-90 capfall
• Chemical spray (different group) pre-bunch
  closure
• Saranade max at verasion?
• Rovral as pre-harvest if required.

22
(No Transcript)
23
Rotten Grapes in the Winery

• The year turned ugly. You have Gray rot in the
  vineyard and want to salvage something.
• Depending on the amount of rot in the harvest, a
  sound wine may still be produced.
• Wait a minutewhy worry anyways?

24
What does Botrytis do to my fruit?

• Botrytis SEVERELY changes fruit composition
• Consumes sugars
• Degrades grape acids
• Degrades grape proteins
• Consumes Nitrogen and Vitamins
• Produces anti-biotic compounds
• Produces gluconic acid
• Produces mucic acid
• Produces polyols
• Produces glucose polymers (glucans)
• Produces many destructive enzymes

25
Major Consequences Enzymes Produced

• Oxidize aromatic compounds and aroma pre-cursors
• Esters hydrolysed
• Terpenes freed and then oxidized
• Thiols bound or destroyed
• Laccases oxidize Phenolic substances
• Browning in white wine
• Oxidative Breakdown in red wines
• Laccase is fairly resistant to SO2 and Bentonite

26
Major Considerations

• Just how rotten is the fruit?
• Easy to see on White grapes
• Not so easy on Red Varietals
• Botrytis may be active inside the berry even
  though no rot is seen the outside
• LACCASE can be monitored
• Test kits that quantify Laccase units
• or can do simple test

27
Dealing with Laccase

• More rot means more Laccase

28
Dealing with Laccase

• Flash pasteurization or Thermovinification
• Heat the must to destroy the enzyme
• Addition of Enological tannins
• Combine with the enzymes to fine them out
• Protection of the must using SO2 (PROPER USAGE)
• More SO2 is required than if the must were clean
  (10g/hL?)
• Many more molecules bind SO2 in must made from
  rotten grapes
• Free SO2 protects wine from Oxidative breakdown
• Ascorbic Acid can compliment SO2 treatment
• Maintenance of free SO2 eventually destroys
  enzyme

29
Laccase - White Wine Considerations

• Minimize Mechanical damage
• Whole bunch press
• Cooling
• Cooling juice lowers Laccase activity
• (Cryoextraction?..)
• Inert gas protection minimize O2 dissolution
• Dry ice at press pan and while settling
• SO2 solution (10g/hL) mixed in properly to juice
  as it is pressed
• (ascorbic?)
• Check for potential browning (Laccase activity)
  while juice is settling

30
Laccase Red Wine Considerations

• Good SO2 addition while filling tank
• Want homogenization
• Minimize pre-ferment maceration
• Yeast Inoculation shortly after tank is filled
• Bad idea to Co-inoculate?
• Check for oxidative breakdown potential
• If wine sensitive to breakdown run off early
• Addition of SO2 at run-off

31
Ferment Considerations - Nutrition

• Botrytis may have consumed much of the Nitrogen
• Test for Yeast Assimilable Nitrogen(YAN)
• If below 140mg/L ? supplement near the end of
  1/3rd ferment
• Add Nitrogen depending on the Brix level of the
  must
• (YAN table)
• Use a product that also adds vitamins (Thiamine
  and Pyridoxine)
• Remember healthy yeasts are best. Oxygen
  during development and fermentation.

32
Ferment Considerations

• Stuck Ferments can occur
• Not enough Nutrients
• Competition with other Yeasts
• Presence of anti-microbial substances
• Build-up of other substances toxic to yeasts
  (fatty acids)
• Possible late season vineyard spray contamination
• A stuck ferment can be a big issue!

33
Ferment Considerations Stuck Ferment

• Monitor your ferment
• Stuck ferment can usually be predicted
• What can be done?
• Yeast hulls or inactivated yeasts
• Still no go?
• Restart Ferment
• Red must should be pressed and lightly sulfited
• White must can be lightly sulfited as well.
• Bacterial contamination not wanted at this time!
• Lysozyme is also an option

34
Other issues?

• Clarification problems are likely
• 1,3- and 1,6- glucans are produced
• These molecules aggregate together (ethanol in
  wine)
• Filterability is dramatically reduced
• Test for filterability
• If needed add enzyme to break down glucan
  molecules
• Other instability
• Mucic acid will be present up to 2g/L
• Can form Calcium Mucate
• If de-acidifying using Acidex or CaCO2 be careful
• may precipitate out of the wine at a later date

35
Questions?