Plant Disease and Insect Clinic
Detection
of Phytophthora in Water Supplies
Commercial growers who suspect that Phytophthora spores may be present in the irrigation water supply for the greenhouse or nursery may test their water supply with the 'Pear Method'
Follow 'Sample submission' information. Clinic fees apply.
Pears
 Preparation: Purchase pears directly from wholesalers such that the pears are coming
directly out of cold storage. It is important that green, rock-hard
pears be used.
 |
| Just before use: Wash
pears gently in warm, soapy, mild dish detergent to remove any fungicide
residues. Rinse
pears in clean water and blot dry with paper towels. |
In
the greenhouse
|
At 2-3 different points in greenhouse. |
|
Collect about 5 gals of water in opaque plastic storage bins (bins
should be cleaned with bleach and rinsed completely). |
|
Water level should be about 4-5 inches in bin. |
|
Float green, rock hard pears on water, about 5 pears/bin for 3 days. |
|
After 3 days, remove pears from water. |
|
Place each pear in a sandwich-size recloseable bag. |
|
Place bagged pears from each water sample in a larger bag to keep
pears from the same bin together. |
In
ponds supplying greenhouse or nusery
|
Supplies: Inner tube, (3/16" or 1/4") poly rope, and citrus-type mesh
bag. |
|
Place 5-7 pears in citrus bag. |
|
Attach bag in center of inner tube with rope straps so that it is
free to settle into the water. |
|
If turtles are in the pond construct a cage of wire mesh hardware
cloth to protect pears from being eaten. |
|
Attach 100' poly rope on either side of inner tube at the corner of
the pond; place tube and bag in water; then have two people walk in
opposite directions away from corner to draw tube out into pond. |
Secure rope to stakes on bank so that tube will remain fairly stationary.
After
3 days, retrieve tubes, pack and ship pears. |
Packing pears for shipment
|
Use individual recloseable sandwich bags for each pear. |
|
Put pears from each location in greenhouse or pond in a larger plastic
bag and mark location accordingly. |
|
Pack in shipping container with plenty of padding to avoid bruising
fruit during shipment. |
|
Ship for next day delivery. |
Ship
to:
Plant Disease & Insect Clinic
1227 Gardner Hall
100 Derieux Place
NC State University
Raleigh, NC 27695-7211 |
Fees
for Pear Bait testing are the same as other samples. Current
Fees
Phone:
919.515.3619
|
.
Plan
sampling so pears can be shipped Monday - Wednesday
 |
 |
| Pears suspended in top of sample water just so fruit are covered. |
Pears after baiting period. |
 |
 |
| Infected pear with brown lesion due to Phytophthora. |
Infected pear tissue ready for transfer to culture plates for Phytophthora isolation. |
Web
page last updated June 2008 |
