Becky Hughes, John Zandstra, Toktam Taghavi and Adam Dale, University of Guelph

Many growers in Ontario have planted dayneutral strawberries in recent years to take advantage of a longer marketing season. Dayneutral production systems are very different than those we have used for years to produce Junebearing strawberries. For dayneutrals, plants are set at a high density on plastic-mulched, raised beds. Cultural practices are used to produce large multi-crown plants for the greatest fruit production. In most of Ontario, fruit is usually harvested in the first year and the spring of the second year in a modified annual system.

Runner removal is a costly but recommended practise in dayneutral strawberry production. A trial was planted at Cedar Springs in southwestern Ontario and New Liskeard in northeastern Ontario in 2014 to examine the effects of runner removal on harvest distribution, harvest efficiency/recovery, yields and plant growth. Runners were removed weekly starting six weeks after planting, three times a season at six, nine and twelve weeks after planting, once a season at ten weeks after planting or not at all.

The effects of runner removal on yields and plant growth depended on the year, cultivar and site. Runner removal treatments were continued in 2015, however there were few treatment effects on yield in the second year at either site.

There were many effects of runner removal in the planting year. This article will concentrate on the effects on yields. At both sites, all fruit was harvested twice a week and sorted into marketable (no rot and regularly shaped with a diameter greater than 1.5 cm) and unmarketable. Fruit in each category was weighed and counted. Berry weights (g/fruit) were calculated for marketable fruit only.

Runner removal increased the yield of Albion in the planting year. Runner removal increased the total and marketable yields of Albion in the planting year at both sites. In Cedar Springs, the total yield of Albion was reduced by 30% when runners were not removed (Table 1).

Table 1. The effects of runner removal at different intervals on the total and marketable yields, and berry weights of Albion and Seascape in Cedar Springs in 2014.

Effects of Runner Removal
Runner removal treatment
Albion yields 2014 (kg m-1)
Albion berry wt. (g/berry)
Seascape yields 2014 (kg m-1)
Seascape berry wt. (g/berry)
Total
Marketable
Total
Marketable
Weekly
1.92 a1
1.72 a
16.4 a
2.33 a
1.99 a
12.7 a
3 times
1.81 a
1.65 a
15.4 a
1.92 a
1.60 a
12.2 a
1 time
1.90 a
1.60 a
15.9 a
1.96 a
1.65 a
12.3 a
Never
1.32 b
1.21 b
15.6 a
2.12 a
1.83 a
12.3 a

1 Numbers within a column with different letters are significantly different.

Seascape responded to runner removal only in the more challenging northern climate in New Liskeard. In the cooler climate, both Albion and Seascape produced greater yields in the planting year with weekly runner removal but not with the less frequent treatments (Table 2).

Table 2. The effects of runner removal at different intervals on the total and marketable yields of Seascape, and berry weights of Albion and Seascape in New Liskeard in 2014.

Effects of Runner Removal
Runner removal treatment
Seascape yields 2014 (kg m-1)
Berry wt.
(g/berry)
 
Total
Marketable
Seascape
Albion
Weekly
1.52 a1
0.89 a
13.2 a
21.1 a
3 times
1.32 ab
0.76 ab
13.3 a
19.4 ab
1 time
1.23 b
0.60 b
13.3 a
19.7 ab
Never
1.25 b
0.64 b
13.8 a
13.8 b

1 Numbers within a column with different letters are significantly different.

The timing of runner removal was more critical at the northern site with early, more frequent runner removal giving the best results.

Removing runners weekly took almost twice as much time as the other two runner removal treatments at both sites. However, the amount of plant material removed by the once-a-season runner removal treatment was six times that of the other two runner removal treatments. The time recorded for runner removal was the time to cut the stolons from a metre of row and didn't include the time to remove the plant material from the field. This would be necessary with once-a-season runner removal given the amount of material present. As the work crew also preferred removing younger runners with less plant material, removing runners every week or two may be the best compromise from a labour and yield point of view.