Hot summers and cork spot in D’Anjous can be a significant challenge in Central Washington. Cork spot is responsible for an estimated $7 to $8 million dollarsi in losses to Anjou production every year. In 2017, cork spot accounted for approximately 33% of Anjou culls. Irrigation frequency and timing, as well as good calcium programs can affect tree growth, productivity and fruit quality in pearsii. Fruit size is also critical for high returns.
• Small fruit
• Inability to conduct tractor work when sloping field stays wet.
• Lack of uniformity, variable weak trees
Impact sprinklers (Rainbird) on 36 foot by 36 foot spacing. Growers generally run 1 row at a time skipping a row as they go across the field and return taking 9 days to irrigate the five-acre field.
R10 micro sprinklers were installed every row on a 20 by 20 foot spacing in a five-acre field encompassing one half of the sloped field in spring 2018.
“Zero run off in the new system.”
“Leaf color was more uniform.”
“Before the quickest we could water was 9 days. Now if we want to we can water the whole block in 2 days (20 lines at a time).” = more flexibility “If we need to push water it is a lot easier.”
“Good to have less water more often.”
IMPACT ON WATER USE
Soil moisture record from 2019. The soil in the standard system tended to stay too wet.
IMPACT ON TREE STRESS
Tree water limitation is measured by using a pressure chamber to measure leaf water potential. Water within the plants moves through a network of cells (xylem) that act like pipes carrying water from the roots. When the soil dries and the roots cannot keep pace with evaporation from the leaves the water in the plant becomes under tension. Tension over 1.2 mpa is considered too high.
Water limitation measured by leaf water potential was lower in the upgraded block (0.79 to 1.13 mpa on July 17, 2018) compared to the standard block (0.81 to 1.7 mpa).
Tree water stress for 2018 (left) and 2019 (right).