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2016 OSU Kabocha/buttercup production and storage trial results.
4/2017
The goal of this project is to identify high-‐yielding, long storing and delicious kabocha, buttercup, and other winter squash varieties for production on Willamette Valley fresh market vegetable farms. Sixteen varieties of kabocha and buttercup squash were grown at four planting densities in a replicated field experiment at the Oregon State University research farm in 2015 and 2016. Data was collected on fruit size, yield, flavor, resistance to storage rots, and duration of storage. In 2016 only, the same 16 varieties were grown under dryland conditions in a separate replicated field experiment.
In 2015 the OSU experiment was managed conventionally. In 2016 it was managed on conventional land using organic practices (with the exception of cucumber beetle management – a synthetic pesticide was applied several times as populations are very large on this farm). There is insufficient certified organic land at the Corvallis research farms. Single-‐density replicated on-‐farm trials were also conducted on two organic farms both years. This article primarily reports on the methods and results from the OSU research station trial.
The irrigated experiment was a repeat of a 2015 experiment.
METHODS
Varieties
Pictured below are the 16 varieties trialed in 2016. For a detailed description of each variety’s characteristics, botanical category, origin and size, please see the results page from 2015.
Design and Management
Irrigated Trial -‐ Each variety was grown at 4 densities with 4 replications in a replicated complete block design. Squash transplants were grown in the greenhouse and transplanted into the field on May 25th. Rows were planted on 5 ft centers; density varied by in-‐row spacing (9 in, 1 ft, 1.7 ft and 2.5 feet between single plants). The plants received 1 inch of supplemental water once per week via overhead irrigation.
Dryland Trial – Each variety was grown at 4 densities with 3 replications in a replicated complete block design. Seeds were direct sown in the field on May 11th. Rows were planted on 7.5 ft centers; density varied by in-‐row spacing (1 ft, 1.5 ft, 2.4 ft, and 3.75 feet between single plants). The field was watered once after seeding and was not irrigated afterward.
Field Maps IRRIGATED EXPERIMENT: 2015 and 2016. 4 densities and 4 replications. Rows on 5 ft centers. 9 in, 1 ft, 1.7 ft, and 2.5 feet in-‐row spacing
5 10 15 20 25 30 35 40 45 50 55 5 5 10 15 20 25 30 35 40 45 50 55
1514 6 2 13 5 15 10 13 2
101 13 7 5 7 7 15 9 16
259 11 12 15 2 9 6 5 11
1014 15 4 9 9 11 8 3 2
353 8 5 1 9 7 3 14 16
1010 8 3 16 10 12 5 14 13
4510 16 7 4 10 1 4 8 12
102 6 12 11 3 1 10 4 6
50 block 1 5 block 2
6013 5 11 6 11 4 8 10 13
106 2 10 8 1 16 9 15 7
7014 15 10 3 1 7 15 12 16
1016 11 12 3 4 13 14 11 4
808 2 9 4 7 1 2 9 3
104 14 9 15 11 6 8 12 5
9016 12 7 1 3 14 5 11 6
1013 1 7 5 5 10 1 2 3
95 5
115 10
120 5
1308 6 3 14 8 2 8 16 12 10 16 2 6 8 6 13 15 2 6
1402 1 7 9 6 9 5 15 1 10 11 4 10 3 8 1 7 8 9
15012 5 11 16 4 13 4 7 14 10 14 7 9 1 2 11 10 16 3
16015 4 13 10 11 10 6 3 11 10 15 5 12 13 3 5 4 12 14
165 block 3 5 block 4
17010 6 3 1 2 6 2 10 8 10 3 8 12 9 10 6 5 2 14
1809 14 4 7 5 16 11 12 3 10 7 15 14 2 6 10 11 1 15
1905 15 13 11 4 4 14 9 15 10 11 5 6 4 1 7 8 12 13
2008 2 16 12 7 13 1 7 5 10 10 1 13 16 9 3 4 16 9
205 5
Golden
G 4 plants/plot
Hone
y Bear 4 plants/plot
DRYLAND EXPERIMENT: 2016. 4 densities and 3 replications. Rows on 7.5 ft centers 1 ft, 1.5 ft, 2.4 ft and 3.75 feet in-‐row spacing
Data Collection
Fruits were harvested during the week of August 29th for the irrigated trial and during the week of September 5th for the dryland trial. All fruit from each plot were weighed and counted at harvest. Fruit were stored in three locations: a walk-‐in cooler with dehumidifier that was maintained at 50-‐55o F and approximately 60% relative humidity, a closed garage kept above freezing air temperature, and an open barn bay (squash from the open bay were moved into a closed barn bay from mid December through early January). Fruit were evaluated monthly from September 2016 through March 2017 for percent rotten or otherwise unmarketable fruit (e.g. soft or wrinkled), and a subsample was evaluated for external and internal color, degrees Brix, and percent dry matter. A chef evaluated some of the varieties for sensory quality on several dates (data not yet available).
Cream of the Crop Honey Bear Sweet Reba
3 8 12 9 9 1 13 7 5ROAD
14 6 2 13 9 10 6 3 1
7 15 14 2 3 14 15 4 9 9 11 12 15 1 9 14 4 7
11 5 6 4 5 10 8 3 16 3 8 5 1 8 5 15 13 11
10 1 13 16 11 2 6 12 11 10 16 7 4 4 8 2 16 12
Honey Bear Jester
6 2 10 8 4 10 2 5 14 8 6 3 14 7 16 11 12 3
16 11 12 3 1 6 1 11 15 2 1 7 9 11 4 14 9 15
4 14 9 15 7 7 8 12 13 12 5 11 16 3 13 1 7 5
13 1 7 5 8 3 4 16 9 15 4 13 10 2 6 2 10 8
Honey Bear Cream of the Crop
13 5 11 6 6 6 2 10 8 16 9 15 7 10 8 12 3 9
14 15 10 3 12 16 11 12 3 13 14 11 4 5 15 14 7 2
8 2 9 4 2 4 14 9 15 6 8 12 5 12 5 6 11 4
16 12 7 1 10 13 1 7 5 10 1 2 3 6 1 13 10 16
Greek Sweet Red Greek Sweet Red
Hilo La
otian
Cream of the
Crop
Sweet D
umpling
Sweet R
eba
Hone
y Be
arDe
licata Sugarlo
af
Hone
y Be
ar
Jester
RESULTS
Yield
Irrigated trial squash yields were higher in 2015 compared to 2016 for all varieties. Yields were exceptionally high in 2015 due to the very hot dry summer. The 2016 summer was much cooler with some humid rainy periods, which caused an early powdery mildew epidemic (starting at fruit set) which reduced yields. Tetsukabuto is an extremely high yielding squash and also powdery mildew resistant, so irritated yields were high in 2016 and double the dryland yield. For other varieties, however, dryland yield was comparable to 2016 irrigated yield as they yielded so poorly in under irrigation in 2016. These varieties include Winter Sweet, Cha-‐Cha, and Burgess. Crown, Gold Nugget and Shokichi Shiro were only grown in 2016
On-‐farm Trials
A subset of the varieties grown in the OSU Kabocha/buttercup trial were grown on three on-‐farm trials along with 11 other long storing winter squash varieties. The yield results from two of the farms are shown below.
Losses to Storage Rots: effects of production and storage environments
Extension bulletins recommend storing winter squash between 50 and 55o F and 60 to 70% relative humidity to avoid chilling injury, but in informal trials squash appeared to store as well or better under closed barn bay conditions. We evaluated the impact of storing all varieties in three different storage environments on losses to storage rots as well as fruit quality.
The Three Storage Environments
Temperature and humidity were monitored in each location. The following figure shows the temperature in each location from November through March. The Walk-‐In environment stayed consistent, while there was more fluctuation in the other two environments. The squash stored under Open Bay conditions were moved temporarily into another closed bay environment (different from the Closed Bay, and maintained at a slightly lower temperature) from mid December through early January as temperatures were expected to be in the low 20s during that period, and then returned to the open bay. Temperatures in the Open Bay fell to below freezing in January resulting in a catastrophic loss of most of the varieties stored there.
The squash were evaluated monthly for storage losses. One of the most important characteristic of winter squash varieties is whether their fruit are resistant to fruit rots. There are serious squash fruit rotters (soilborne fungi) in the Willamette Valley. Fruit that are not resistant rot soon after harvest. Most winter squash varieties ARE NOT resistant to these rots so should not be grown if they cannot be sold immediately after harvest. Another important characteristic is whether or not the fruit is long storing (can maintain eating quality for a long storage period).
Squash fall into 4 general storage categories
1. Very rot resistant AND long storing (Tetsukabuto and Winter Sweet) 2. Moderately rot resistant AND long storing (Sweet Mama) 3. Not rot resistant but long storing (Sunshine -‐ it might only be possible to store these if grown
dryland) 4. Not rot resistant, not long storing (Uncle David, don’t grow these to store!)
Below are figures representing an example of each of the 4 types of squash listed above. The y-‐axis shows the yield (tons/acre) at harvest (late August) and as the squash are stored throughout the fall and
winter. Total yield is adjusted to reflect squash storage losses. As shown in the figures, Tetsukabuto is the star performer. It is high yielding, completely resistant to storage rots, and long storing. Tetsukabuto, interestingly, lost quality due to dehydration (not storage rots) when grown dryland and stored in the Walk In. Sweet Mama is high yielding (it yielded better in 2015 than in 2016) and stores well into December when grown under irrigation, but does not store nearly as long as Tetsukabuto. However, Sweet Mama grown dryland in 2016 stored as long as Tetsukabuto. Sunshine is high yielding but very susceptible to storage rots here in the Willamette Valley. However, it was less susceptible to storage rots and much longer storing when grown dryland in 2016. Uncle David is not high yielding, rot resistant, or long storing when grown here in the Willamette Valley.
The figure below shows the yield at the time of harvest minus the percent loss in storage in late January.