| The Effect
of Various Treatments on the Mold Growth of Red D'Anjou Pears |
Researched by Colin A.
2003-04 |
|
PURPOSE
The purpose of this experiment was to determine the best way to reduce
blue mold (Penicillium), and gray mold (Botrytis cinerea) on red DAnjou
pears, in open air.
I became interested in this idea when I talked to Doug Anyan, and he
told me of a similar experiment that he had done at his work.
The information gained from this experiment would benefit most fruit
growers, especially pear growers, by reducing their reliance on fungicides.
HYPOTHESIS
My first hypothesis was that vegetable oil would be the most effective
treatment to stop mold on post harvest, red DAnjou, pears.
I based my hypothesis on the many experiments done with oil wraps that
I have read about, and the fact that they have all been very effective.
My second hypothesis was that the chlorine solution would be the worst
treatment to stop mold on red DAnjou pears.
I based my hypothesis on the thought that the chlorine solution would
run off the pear, and provide little protection after that. I also
read that when chlorine is used it may not be effective enough.
EXPERIMENT DESIGN
The constants in this study were:
* The type of pear being used (red DAnjou)
* The temperature at which the pears will be set out (21 degrees Celsius)
* The place were the products where tested
* The procedures for measuring the mold growth
* The amount of trials per Treatment
* The way of inoculating the pears
The manipulated variable was the type of product used to stop blue and
gray mold.
The responding variable was how much blue or gray mold developed on
the pear.
To measure the responding variable I made a visual scale (1-10. One
being little or no mold, and 10 being mold encrusted), and rated each pear.
I then averaged the ratings.
MATERIALS
| QUANTITY |
ITEM DESCRIPTION |
| 40 |
Red DAnjou pears |
| 4 |
Pear Trays |
| 1 |
roll of paper towels |
| 1 |
bottle of vegetable oil |
| 1 |
Pair of rubber gloves |
| 1 |
Set of safety goggles |
| 1 |
facemask |
| 1 |
Screw driver |
| 1 |
50-ounce container |
| 1 |
Pitcher |
| 1 |
sink |
| 128 |
ounces of water |
| 8.8 |
milliliters of Clorox chlorine (500 parts per million) |
| 4 |
ounces of powdered zinc oxide |
| 1 |
notebook |
| 1 |
syringe |
| 12 |
disposable, glass, pipettes |
| 4 |
ounces of zinc oxide powder |
| 1 |
extremely moldy pear |
PROCEDURES
1. Put on gloves, goggles, and mask.
2. Pour 32 ounces of water into the mixing container (the 50oz container).
3. Add 8.8 ounces of chlorine (500 parts per million).
4. Take one pear and (using your dominant hand) dip the pear in the
solution for 7 seconds.
5. Repeat step 4 (make sure to pick up the next pear with the hand
that has not been in the solution, so all the pears do not have that solution),
for 9 more pears.
6. Pour out the container, and wash it out with tap water.
7. Wash gloves.
8. Pour 32oz of water into the mixing container.
9. Repeat steps 4-5.
10. Repeat step 6
11. Repeat step 7
12. Repeat step 2
13. Take 4oz of zinc oxide powder, and pour it into the container.
14. Stir the solution.
15. Repeat steps 4-5
16. Repeat step 6-7
17. Take a paper towel, and saturate it with the vegetable oil.
18. Take one pear and wipe the towel over it (making sure to get the
stem and bowl).
19. Repeat step 18 for the remaining pears.
20. Take a disposable pipette and put the tip of it into the mold,
and puncture the fruit.
21. Take a screwdriver and enlarge the wound, made by the pipette.
22. Repeat steps 19, and 20 for three pears in each of the groups.
23. Clean gloves, and throw them away (so no bad stuff is in the garbage)
24. Clean the screwdriver, and dispose of the pipettes.
25. Let the pears sit for 14 days.
26. After the 14 days take all the pears and, using the visual guide
and safety procedures (in step 1), grade each pear.
27. Repeat steps 2 and 3 and soak one pear group, and dispose of them.
28. Repeat step 27 for the remaining pear groups.
RESULTS
The original purpose of this experiment was to determine what treatment
would prevent mold from growing on a red DAnjou pear.
The results of the experiment were that oil was the best treatment to
prevent mold growth on red DAnjou pears. The results of this experiment
also indicate that zinc oxide was the worst treatment to prevent mold growth
on red DAnjou pears
See the table and graph below
CONCLUSION
My first hypothesis was that the oil treatment would be the best at
preventing mold. My second hypothesis was that the chlorine would
be the worst at preventing mold.
The results indicate that my first hypothesis should be accepted because
the oil treatment had an average of .15. The results of this experiment
also indicate that my second hypothesis should be rejected, because zinc
oxide was the worst treatment to prevent mold.
Because of the results of this experiment, I wonder what would happen
if I where to use a different pear, instead of the Red DAnjou.
If I were to conduct this project again I would test a different type
of pear, and see if the same results occurred. I would also use a
fungicide, and see how well it compares to the other treatments.
|
RESEARCH REPORT
Introduction
Pears are an important part of our economy. Pears are also a
great tasting food. Without a tasty treat life wouldnt be fun.
Although there are many ways that pears can go bad, the two most common
are Blue and gray Mold. There are many ways to treat pears to resist
mold.
MOLDS AND ROTS
Pears
Pears are a very interesting fruit. They are a very fleshy fruit.
Pears come in many different shapes, and sizes, they can have the most
common shape, where the stem is pointed, and the bottom is much more rounded.
They also can look just like an apple, and can be as small as a cherry.
There are hundreds of different types of pears. Many of them have
a core like an apple, containing, on average, about 10 seeds. A pear
tree can be as tall as 45 feet, and 25 feet wide, at the base. Pear
trees can live a very long time, sometimes up to 75 years. The most
common pears are Bartlett, Comice, Anjou, Bosk, Hardy, Seckel, and Winter
Nelis. It is not known when pears were first found, but there are
hints. One poet wrote about the fruit in the 700s B.C. Washington
State is the number one producer of pears per year (14,830,000 bushels)
in North America.
Blue Mold
Blue mold is also known as Pennicilium. It is not a nesting mold
(does not spread from fruit to fruit), unless the pears are in a water
system, and one has a wound. Blue mold is first formed through the
stem. Blue mold can grow on pears much longer after harvest than,
on apples. This is because the pears stem remains moist, while the
apples, dries up. Blue mold accounts for 24% of damaged harvest.
Gray Mold
Grey mold is also known as Botrytis Cinerea. Unlike blue mold,
gray mold is a nesting fungus. As with blue mold, Botrytis Cinerea
can be transferred by a water system. Gray mold is likely to occur
in low temperatures. Grey mold accounts for 55% of damaged harvest.
Mucor Rot
Mucor Rot is also known as Mucor Piriformis. Mucor rot usually
begins in the soil of the areas where the fruit grows. If the soil
is extremely moist, and there are many decaying things on the ground mucor
rot is very possible. Mucor rot can also develop in winter.
It can also be spread to bins that have been laid on the ground.
The rot can be absorbed by the bin, and contaminate all pears in the bin.
Mucor rot is accountable for 8% of damaged crop every year.
Bulls-Eye Rot
Bulls-eye rot is also known as Pezicula Malicorticis. This is
a slow growing fungus. Bulls-eye rot is not usually discovered until
storage. Although it usually starts when the pears are tiny.
Bulls-eye rot is indicated by the concentric rings, found inside the contaminated
fruit.
Coprinus Rot
Coprinus rot is also known as Coprinus Psychromorbidus. It is
commonly mistaken for bulls-eye rot. Even though coprinus rot is
similar to gray mold, in the fact that it is a nesting mold. This
rot comes from mushroom spores, found from a mushroom in the orchard.
It usually infects the fruit one month before harvest. Although it
is commonly mistaken for bulls-eye rot the main difference is that coprinus
rot looks like a cobweb like fungal growth on the surface of the fruit.
TREATMENTS
Chlorine
Chlorine can be a very effective way to treat for mold and rot. It
is a contact killer. It is commonly used in fruit dump tanks.
Although the concentration of the chlorine must be correct for it to be
effective (if the spores are away from the main concentration then many
fruit will still be infected). Chlorine minimizes the amount of dirt
in the tank, which reduces the chance of infection. Chlorine does
not, however cover the pears in the long run, such as from storage to the
market.
Oil
Oil is a commonly used method of treating fruit for mold prevention.
Although usually oil itself is not the only thing on the fruit. Usually
it is a special wrap that is impregnated with oil that remains on the fruit.
Oil is a contact killer, so if there is any mold on the pear then it should
eliminate it. Making it complicated for other molds to grow on it.
Zinc Oxide
Zinc oxide is not a commonly used treatment for the prevention of postharvest
mold, and decay. A common type of zinc oxide is Nutraphos-24.
Summary
In conclusion, mold and rot are very damaging things to the Washington
economy, and agricultural economics around the world. With all the
various types of mold and rot it is very complicated, if not impossible,
to solve them all. Although thanks to many studies there are ways
to stop the leading damages of harvest, and many other types of damages. |
|
BIBLIOGRAPHY
Acetic acid shows promise for control of fruit decay. Dec,26,2004.
Kupferman Eugene Dr., Robert Spotts: and David Sugar. Practices to
reduce post harvest pear Diseases. Jan,25,2004. http://postharvest.tfrec.wsu.edu/pgDisplay.php?article=J6I2B
Kupferman, Eugene Dr. how to prevent diseases of fruit in storage.
Dec,26,2003. http://www.goodfruit.com/link/Marl-99/speciall.html
Lennox, Cheryl and Spotts, Robert. Botrytis Gray Mold as a Post
harvest Pathogen in DAnjou Pear. Dec,26,2003. http://postharvest.tfrec.wsu.edu/pgDisplay.php?article=PC97M
Sanderson, Perter G Dr. and Bennett, Diane L. Effect of
paper wraps on post harvest decay and disorders of Anjou pear fruit.
Dec,26,2003. http://postharvest.tfrec.wsu.edu/pgDisplay.php?article-W99A02 |
ACKNOWLEDGEMENTS
I would like to thank the following people for helping make my project
possible:
* My parents for driving me to the various places were I needed to
be
* Mr. Newkirk for helping me with many aspect of my project
* Doug Anyan for allowing me to use his research lab to conduct my
experiment
* Tom Eisley, John Baranowski, Dr. Gamlem, and Joel Hollingsworth for
granting my SRC approval
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