Figure 3. a) ‘hopperburn’ caused by potato leafhoppers, b) damage to leaves and cones caused by Japanese beetles, c) Alternaria cone disorder (severity rating of 1-5, from left to right).

a b c

Hop cultivar evaluation Cathy Bakker1, Evan Elford2 and Mary Ruth McDonald1

1Department of Plant Agriculture, University of Guelph; 2Ontario Ministry of Agriculture, Food and Rural Affairs

Introduction

Materials and Methods

Results and Discussion

Funding for this project was provided by the New Directions Research Program, OMAFRA.

Hops, the female inflorescence of the hop plant (Humulus lupulus L.), are used in the brewing process and provide unique flavour and aroma to beer (Figure 1). Hops were grown in Ontario until the 1930’s when acreage decreased due to disease problems and market pressures. Recently there has been a renewed interest in hop production predominantly for micro breweries. There are over 20 hop growers in Ontario but as a new industry, they require information to identify well adapted cultivars. A cultivar trial was planted in 2013 to address this priority. This poster presents data from the second year of the trial.

Objective Evaluate commercial hop cultivars for: a) susceptibility to insect pests and diseases, b) yield and visual quality of cones.

• A hop yard was established at the Simcoe Research Station in May 2013

• 10 cultivars: Cascade, Hallertauer, Sterling, Northern Brewer, Zeus, Crystal, Chinook, Galena, Centennial, Bertwell (naturalized selection)

• Spacing: between row 4.5 m, in-row 1 m • Two 5.5 m tall strings per plant, 3 bines trained per string (Figure 2) • Plots scouted weekly and insect and disease severity was assessed • Plots harvested in mid-late August when cones reached 20-25% dry

matter, harvested cones then dried down to 8% moisture

Figure 1. a) hop burrs; b) cones; c) cross section of an immature cone.

a c b

In 2014, potato leafhoppers, Japanese beetles and two-spotted spider mites were the most common insect pests found (Figure 3). The first potato leafhoppers were found on 4 June, but numbers remained low until late June-early July when the population increased rapidly (Figure 4a). Two-spotted spider mite eggs and nymphs were first found on 10 July but numbers remained low throughout the season and there were no differences in TSSM counts amongst the cultivars.

Conclusions • Potato leafhoppers, Japanese beetles, and Alternaria cone disorder

were the most significant production challenges in 2014 • There were significant differences in insect and disease susceptibility

amongst cultivars • Chinook had the lowest levels of Japanese beetle feeding damage • Potato leafhopper counts were lowest on Bertwell and Galena • Severity of Alternaria cone disorder was lowest on Cascade and Bertwell

• Cascade, Zeus, Galena and Chinook produced the highest yields in 2014

Figure 2. a) trained bines, May 2014; b) 13 June, 2014; c) 1 Aug, 2014; d) Wolf hop harvester; e) hop cones ready for drying.

Downy mildew was observed in late May to early June, but disease was sporadic and no differences were observed amongst the cultivars. Cascade, Zeus, Galena and Chinook produced the highest yields in 2014. However, cone quality was poor due to widespread Alternaria cone disorder (Figure 3 c). All cultivars were affected, however severity was lowest on the cultivars Cascade and Bertwell (Figure 6).

a

b c

d e

Figure 4. a) Average number of potato leafhoppers (PLH) and two-spotted spider mites (TSSM) per leaf over the growing season; b) Severity of Japanese beetle (JB) feeding damage; c) Number of potato leafhoppers (PLH) per leaf, d) Severity of hopperburn (0-5): 0 = no damage, 1 = minor yellowing along leaf margin, 2 = moderate yellowing, 3 = severe yellowing and minor necrosis/curling, 4 = severe necrosis and curling, 5 = advanced necrosis or leaf death. Columns labelled with the same letter are not significantly different at P = 0.05, using Fisher’s Protected LSD test.

0

0.5

1

1.5

2

2.5

3

0

5

10

15

20

25

30

35

40

45

28-M

ay04

-Jun

12-J

un19

-Jun

26-J

un02

-Jul

10-J

ul16

-Jul

23-J

ul31

-Jul

07-A

ug14

-Aug

21-A

ug

Num

ber o

f PLH

per

leaf

Num

ber o

f TSS

M p

er le

af

TSSM eggsTSSM nymphs + adultsPLH nymphs + adults

a

0

0.5

1

1.5

2

2.5

3

3.5

kg/p

lant

at h

arve

st m

oist

ure

0

1000

2000

3000

4000

5000

6000

7000

8000

Kg/h

a at

har

vest

moi

stur

e

c

a b

Figure 5 a) Cone yield (kg per plant) at harvest moisture, b) cone yield (kg per ha) at harvest moisture, c) cone yield (g per plant) at 8% moisture, d) cone yield (kg per ha) at 8% moisture. Columns labelled with the same letter are not significantly different at P = 0.05, using Fisher’s Protected LSD test.

Japanese beetle feeding damage was least severe on Chinook, followed by Bertwell and Cascade (Figure 4b). The number of potato leafhoppers per leaf was lowest on Bertwell and Galena and severity of hopperburn was lowest in Bertwell, Galena and Centennial (Figure 4 c,d). Overall, aroma cultivars tended to be more attractive to leafhoppers and exhibited more severe symptoms of feeding damage.

0

10

20

30

40

50

60

Perc

ent o

f pla

nt w

ith J

B da

mag

e b

a

b b bc

cd d de de

e e

0

0.5

1

1.5

2

2.5

3

Num

ber o

f PLH

per

leaf

a a

ab abc

abc

bc bc c c c

0

0.5

1

1.5

2

2.5

3

3.5

4

Seve

rity

of h

oppe

rbur

n

d

a a a

ab ab

b

c cd

d d

a ab

bc

c

d de de

de de e

a ab

bc c

d de de

de de e

0

100

200

300

400

500

600

700

800

900

g/pl

ant a

t 8%

moi

stur

e

c a a a

ab

b bc

bc

c c c

0200400600800

100012001400160018002000

Kg/h

a at

8%

moi

stur

e

d a a a

ab

b bc

bc

c c c

Figure 6. Severity of Alternaria cone disorder rated from 0-5, with : 0= no disease, 1= <10% of bracts with brown lesions, 2= 11-25%, 3= 26-49%, 4=50-79%, 5= > 80%. Columns labelled with the same letter are not significantly different at P = 0.05, using Fisher’s Protected LSD test.

0

0.5

1

1.5

2

2.5

3

Seve

rity

of A

ltern

aria

con

e di

sord

er

a a b b

c d e f

g

h