In northern states, spinach is normally planted in early spring for late spring harvest or in summer for autumn harvest. Spring plantings are often limited by the difficulty of working cold, wet soils and many cultivars bolt in the long daylengths of late spring. Summer crops must be established during periods of very high soil temperature and low soil moisture and require frequent irrigation. Some Willamette Valley growers have successfully planted spinach in late summer for autumn harvest or in autumn for early spring harvest. Ideally, stands can be established during periods of relatively favorable soil temperature and moisture and plants harvested before long days induce bolting. Either system would allow for double cropping (three crops in two years) when combined with beans, corn, or other vegetables, and would allow for more efficient use of processing facilities. These trials were undertaken to evaluate several spinach cultivars or lines for autumn or overwinter crops and to obtain better knowledge of the cultural problems involved, particularly weed control in the overwinter crop.
Methods
In both autumn and overwinter trials, 24 cultivars or lines of spinach were seeded on 1.0 m raised beds of Willamette silt loam, pH 6.0. Planting dates were August 24 and October 3, 1981. Plot areas received a broadcast, incorporated application of 840 kg/ha of 10-20-10 and 4.5 kg/ha of cycloate before final bed shaping. Four replications were planted in randomized complete block design with two rows on each bed. Plot size was 3 m2. Clorpropham at 1.1 kg/ha was applied after seeding. Calcium nitrate was sidedressed on the autumn trial plots at 34 kg N/ha on September 10 and 30, 1981, and on the overwinter plots at 56 kg N/ha on January 25, March 11, and April 2, 1982. Fluid lime at 1,120 kg CaC03/ha was applied to the overwinter trial on January 18, 1982. Autumn trials were harvested and rated on October 14 (XPH 1285) and October 20, 1981; overwinter trials were rated on April 16 and harvested on April 28, 1982.
Results and Discussion
Overall growth and quality were somewhat disappointing in both trials. This may have been caused by slightly marginal soil pH and resultant nutritional problems. The yellow-tipped leaves on most varieties probably were caused by low pH. In addition to yields and plant height, several quality characteristics were evaluated on a five-point scale. A deep green color is an important characteristic for either processing or fresh market and is related to soil pH and nitrogen uptake. Unfortunately, deep green color is also associated with the savoy or crinkle leaf character which is not desirable in spinach for processing. Savoy types are difficult to clean but semi-savoy types may be acceptable. Erect, rather than prostrate, growth habit is important for achieving a high percentage cut out from the field, whether machine or hand-harvested. Prostrate leaves also accumulate more dirt. The ideal cultivar, then, would be high-yielding, non-bolting, erect, deep green, and with large, uniform leaves.
The most outstanding line in the autumn trial was XPH 1285 from Asgrow. It yielded well, had long, large, upright leaves, good uniformity, and average or better color, but not deep green. Other promising lines included Early Hybrid 424 (except for mediocre color), 7R, ACX61, and St. Helens (Table 1).
Bolting was not a problem in the autumn trial because of short days and low temperatures. The cycloate-clorpropham herbicide combination provided excellent weed control and cultivation was not needed. Disease and insect problems were minimal and no fungicides or insecticides were applied. In view of the reduced bolting tendency, autumn spinach may be a better choice than spring planting for processing spinach in the Willamette Valley.
Table 1. Yield, Plant Height at Harvest, and Quality Factors of Autumn-harvested Spinach, 1981 LeafY Cultivar or Yield Height ColorZ VigorY Uni- LeafY GrowthW Line (MT/ha) (cm) formity size habit 7R 11.4 15 3.3 3.0 2.7 2.3 3.3 AC X59 8.5 12 2.3 2.0 3.7 2.3 3.0 AC X61 11.1 16 3.0 4.0 3.7 4.0 3.7 Baker 5.5 11 3.3 1.7 3.7 3.0 1.3 Big Leaf 10.6 13 2.3 2.0 2.0 1.3 2.7 Chinook 10.1 13 4.3 2.7 3.0 3.0 2.3 Dynamo 13.0 16 1.7 3.7 4.0 3.3 3.0 Early Hybrid 7 12.7 14 4.0 3.0 3.0 2.3 3.0 Early Hybrid 424 15.7 18 2.7 4.3 4.0 4.0 4.0 18D-X7 12.7 17 2.0 3.7 3.3 3.3 3.7 18D-X44 12.7 12 3.0 2.0 2.0 2.3 2.3 18D-X49 13.0 14 3.0 2.7 1.3 2.7 2.7 18D-X56 11.4 14 2.7 2.3 2.0 3.0 2.0 18D-X57 7.8 12 2.7 2.0 1.7 2.3 2.7 18D-X59 9.1 14 3.0 2.0 3.0 2.7 2.3 18D-X61 9.5 11 3.7 1.7 2.7 1.7 2.0 18D-X62 11.7 14 2.3 2.0 1.7 2.3 2.0 High Pack 11.4 14 2.3 3.3 2.7 3.0 2.3 Melody 7.8 11 4.3 1.3 4.0 2.0 1.3 R 2578 9.1 11 3.3 1.0 4.0 1.3 2.3 St. Helens 11.4 15 2.7 3.3 4.0 3.0 3.7 Symphony 13.0 13 3.7 1.7 4.0 1.7 3.0 XPH 1285 20.9 32 3.3 4.7 4.3 3.3 4.7 XP 3057 10.8 14 3.0 2.3 3.7 2.3 2.7 LSD (0.05) 2.6 6 0.8 0.9 1.2 1.0 1.0 Zl = pale, yellow; 5 = dark, green Y1 = least vigorous or uniform; 5 = most vigorous or uniform X1 = smallest; 5 = largest W1 = prostrate; 5 = upright
The most outstanding line in the overwinter trial was also XPH 1285. However, it tended to bolt early. Other promising lines included 7R, Chinook, Emerald Queen (except for mediocre color), FM 18DX7 (except for color), Hybrid 424, and Symphony (Table 2). Lines exhibiting significant bolting at time of harvest included XPH 1285, 7R, Chinook, FM18DX44, FM18DX62, and Jake. Lines performing well in both autumn and overwinter trials were XPH 1285, Hybrid 424 and 7R.
The cycloate - clorproham herbicide combination provided good weed control and only one spring cultivation was needed. Disease problems were moderate, with mildew the major problem.
Despite the intensive management which may be needed, overwinter spinach production on well-drained soils may also be a feasible alternative to spring plantings for processing spinach. Major advantages are better planting conditions, earlier harvest, and reduced bolting. Disadvantages include the necessity to keep the field weed free and fertilized during periods when field operations are difficult. Harvest would likely occur under muddy conditions.
Table 2. Yield, Plant Height at Harvest, and Quality Characteristics of Overwintered Spinach, 1981-82 Leaf Plant Yield Height ColorZ VigorZ unifor- unifor- LeafY GrowthX Cultivar (MT/ha) (cm) mity mity size habit 7R 19.8 17 4.0 4.0 3.8 3.5 4.0 4.0 ACX59 12.9 11 2.8 2.8 3.5 2.8 2.8 2.5 ACX61 7.4 12 3.3 2.8 3.8 2.8 3.8 3.0 Avon 12.3 13 4.0 2.5 3.5 2.3 3.0 2.8 Baker 11.9 12 3.8 3.0 3.3 3.0 3.3 2.5 Big Leaf 13.4 12 3.0 2.5 3.0 2.5 2.5 2.8 Chinook 16.8 17 3.0 3.8 4.0 3.0 3.8 3.5 Dynamo 9.5 11 1.3 2.8 3.3 3.0 3.5 2.3 Early Hybrid 7 14.4 12 3.5 2.5 3.5 2.5 2.5 3.3 Early Hybrid 424 14.7 17 2.8 3.5 3.5 3.8 3.3 4.0 Emerald Queen 18.8 17 2.8 3.3 3.8 3.5 3.3 3.3 18DX7 18.3 18 2.8 3.8 3.8 3.0 3.8 3.0 18DX44 15.6 17 2.0 3.5 3.8 2.8 3.3 3.8 18DX56 11.1 12 3.0 2.8 2.8 2.8 3.0 2.8 18DX59 14.7 14 3.3 3.0 3.8 3.0 3.3 3.3 18DX61 13.6 11 3.8 2.3 2.8 2.3 2.3 2.3 18DX62 13.1 14 2.8 3.3 3.3 2.5 3.3 3.3 High Pack 13.1 15 2.8 2.5 3.8 3.8 3.3 3.3 Jake 16.1 14 3.5 2.8 3.8 3.0 2.5 4.0 R 2578 10.6 13 2.8 2.8 3.0 2.0 2.8 3.3 St. Helens 9.6 14 3.5 2.5 4.0 2.8 3.0 3.5 Symphony 14.1 14 4.0 3.0 4.3 3.5 2.8 3.8 XPH 1285 38.1 32 3.5 5.0W 5.0 5.0 4.0 5.0 XP 3057 13.4 13 3.0 3.3 3.5 2.3 3.5 3.0 LSD(0.05) 3.2 4 1.1 1.3 0.8 1.0 0.9 1.1 Zl = pale, yellow green; 5 = dark green Y1 = least vigorous, uniform etc.; 5 = most vigorous, uniform, etc. X1 = prostrate, 5 = upright Wbolting Table 3. Source, Leaf Type, and Comments on Spinach Lines, 1981-82 Cultivar or SourceZ Leaf type Comments line 7R 1,2 semi-savoy Fairly good variety, small leaves. Just started to bolt in overwinter trial. AC X59 1 smooth Average. Leaves had yellow tips. AC X61 1 smooth Above average in all categories but poor stand. AvonY 1 semi-savoy Variable color but usually good. Baker 1 smooth Prostrate, lacking in vigor. Big Leaf ? slight savoy Small (!) leaves with yellow tips. Chinook 1 semi-savoy Good color except for yellow tips. Average otherwise. Bolting just starting in overwinter trial. Dynamo 5 smooth to Fairly good all around except for slight savoy poor color. Early Hyb. 7 1 savoy Pretty good color. Leaves too savoy for processing. Early Hyb. 424 1,4 smooth Better than average except for color. Emerald QueenY 5 smooth Variable color, otherwise above average. FM18D-X7 3 smooth Above average except for poor color. FM18D-X44 3 semi-savoy Leaves had yellow tips. Bolting just starting in overwinter trial. FM18D-X49X 3 slight savoy Average. FM18D-X56 3 semi-savoy Average. Leaves had yellow tips. FM18D-X57X 3 slight savoy Leaves had yellow tips FM18D-X59 3 slight savoy Leaves had yellow tips, but above average quality overwintered. FM18D-X61 3 savoy Better than average color, but poor otherwise. FM18D-X62 3 semi-savoy Poor-fair overall. Bolting just starting in overwinter trials. High Pack 2 slight savoy Lower leaves pale, others with yellow tips. Broad, triangular leaves. JakeY 1 slight savoy Better than average color. Seed stalks just forming. MelodyX 4 very savoy Excellent color, lacks vigor, too savoy for processing. R 2578 5 semi-savoy Small leaves with yellow tips. Variable. St. Helens 1 very smooth Above average variety, but color and yield only fair. Symphony 5 smooth Small leaves with yellow tips. XPH 1285 2 very smooth Long petioles, very early, tendency to bolt early. Long, triangular leaves. XP 3057 2 smooth to Yellow-tipped leaves, average. slight savoy Z1 = Alf Christianson, 2 = Asgrow, 3 = Ferry Morse, 4 = Harris, 5 = Rogers Bros. Seed lot used in trial was from first source listed. YOverwinter trial only. XAutumn trial only.
For the 21 lines included in both the autumn and overwinter trials, 16 yielded more as an overwinter crop than as a fall crop, although harvest was at similar maturity. Some of this yield increase may have been caused by better stands. However, overall yields and plant vigor were still somewhat disappointing when compared to yields in some growing areas. Low soil pH probably contributed to low yields and marginal quality of some lines. In particular, the cultivars Big Leaf and Hybrid 424 have performed better at higher soil pH.