Small Fruit Session

1:00Welcome; Moisture Management in Maine Lowbush Blueberry Lily Calderwood - University of Maine

1:15Water Management and Soil Health for Strawberry Production Nate Nourse - Nate Nourse Consulting

1:30 Soil Moisture Monitoring in Highbush Blueberries Ben Waterman - Waterman Orchards

1:45 The Impact of Water on Disease Pressure Alicyn Smart - University of Maine

2:00 Discussion

Moisture Managementin Lowbush (Wild) Blueberry

Dr. Lily Calderwood Wild Blueberry Specialist

University of Maine Cooperative ExtensionSchool of Food and Agriculture

Most fields are not irrigated.

In a drought year, berries fall through the rake. 30% crop loss in 2017.

Blueberry Patchwork

• Diverse fields• 1500 individuals/field• 40,000 acres in Maine• Range of drought tolerance

Shallow Soil

• Podzol• 2-3 inch OM• 10-12% OM• Sand/gravel below

Can go from saturated to drought conditions in 30 hours

How do farmers overcome this VERY well draining soil?

1. Increase Water Holding Capacity of Soil

A. Soft wood mulch • Low pH • Holds water• Builds OM

1. Increase Water Holding Capacity of Soil

B. Mowing• Holds water• Builds OM

2. Irrigation (only on large farms)• 0.5 – 1.0 inch required per week (Hunt 2006)• Guns used for frost protection in May during bloom • Guns used for irrigation in June and July • Significant sand + gravel aquifers below (reliable source)

Nelson Automated Guns

Research from the 1950’s showing increase in growth with irrigation. (Hunt 2006)

Non-IrrigatedIrrigated

Can We Predict Plant Stress Using Drones? 2019 First Year of Study• Irrigated Field (Airport 77 acres) and Non-irrigated Field (Baxter 40 acres)• Spectral and thermal drone flown at 175 – 200 ft • On-ground data collection: pest scouting, leaf temp, soil moisture,

photosynthesis • Flight and on-ground collection dates:

Early May: baseline flightMid May/Early June: Peak BloomLate June: Green FruitEarly July: Color BreakEarly August: Pre-harvest

Ground and Air Sampling

Irrigated

Non-Irrigated

Elevation

Non-Irrigated

Irrigated

Thermal

Dark red = warmWhite = cold

Non-Irrigated

Irrigated

NDVI Healthy plant = 0.7

Non-Irrigated

Irrigated

Yellow = wetPurple = dry

Moisture Stress Index

Non-Irrigated

Irrigated

Leaf

Wat

er P

oten

tial

Leaf Temperature Graph: Y. Zhang

Observations to Date

• Variable on ground data• Wet spring dried out in July-Aug

• Irrigation did not make a difference in 2019

• Leaf temp may be a good predictor of leaf water potential• Preliminary leaf water potential range of lowbush blueberry:

1.6 Mpa = moist to -2.0 Mpa = dry

Thank You!

Dr. Yong Zhang, UMaine Plant PhysiologistDr. Matt Wallhead, UMaine ExtensionWyman’s of Maine UMaine Research Reinvestment Fund

Water Use in Wild Blueberry

• Wymans 6.4.19• NDVI scale -1 to 1 (healthy). 0.7 is a healthy plant• MSI = moisture stress index (there are many out there)• Ortho = natural cover • DEM = elevation• Irrigated = right, Airport• Nonirrigated = left, Baxter check• Variable on ground data, leaf temp was a good predictor of leaf water

potential. Leaf water potential range: John has a graph showing 1.6 = moist -2 = dry