A standard short-day type of strawberry plant characterized by its capability of exceptionally high yield of very large fruit, firmness and particularly fine flavor. The plant is of interest in all major strawberry fruit growing areas.

DESCRIPTION 
This invention relates to a new and distinctive short-day type strawberry 
cultivar designated as `Oso Grande` (hereinafter to be called `Oso` in 
this document) which is the result of a cross of `Parker` (U.S. Plant Pat. 
No. 5263).times.Cal 77.3-603 made in 1981. . The pedigree is as follows: 
##STR1## 
`Oso` first fruited at the South Coast Field Station in 1982 where it was 
selected and designated originally as Cal 81.43-603. It was tested later 
as advanced selection C43. 
`Oso` has been propagated asexually by runners and has been tested at 
various University of California field stations and facilities and to a 
limited extent in a few growers' fields under Test Agreement.

`Oso` is medium early fruiting and has performed well in winter and summer 
planting experiments in south and central coastal California. It is later 
than `Chandler`, and both are later than `Douglas`. 
Plants and foliage: Leaf color and characteristics from late summer nursery 
plants of `Oso` are compared with those of `Douglas` Pajaro`, `Chandler` 
and `Parker` in Table 1. 
TABLE 1 
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DOUG- PA- CHAND- - 
OSO LAS JARO LER KER 
______________________________________ 
Color 5GY 2.5GY 5GY 2.5GY 2.5GY 
4/3 6/8 4/3 4/3 5.5 
Shape(length/ 
1.07 1.28 1.14 1.16 1.20 
width) 
Base angle of 
59.degree. 
50.degree. 
57.degree. 
58.degree. 
43.degree. 
terminal leaflet 
Size of terminal 
77 83 85 77 84 
leaflets 
Serrations of 
9.5 11.0 10.8 10.2 11.9 
terminal leaflets 
Petiolule 16.7 12.0 15.3 9.2 11.9 
length (MM) 
Petiole 235 241 145 177 198 
length (MM) 
Bract leaflet 
.77 .64 .71 .65 .57 
position 
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As shown above `Oso` leaves are about the same color as those of `Pajaro`, 
darker and less yellow than `Chandler`; similar to `Douglas` and `Parker`; 
(Munsell Color System--Nickerson Color Fan). Terminal leaflets are more 
nearly round than those of `Douglas`, `Pajaro`, `Chandler` or `Parker` as 
shown by length/width measurements and half-blade terminal leaflet basal 
angles. `Oso` terminal leaflets are about the same size as those of 
`Chandler` and smaller than those of `Douglas`, `Pajaro` and `Parker` as 
determined by extracting the square root of the length.times.width 
measurements. Half terminal leaflet serration numbers are fewer than those 
of `Douglas`, `Pajaro`, `Chandler` and `Parker`. Petiolules (terminal 
leaflet stems) of `Oso` are much longer than those `Chandler`, `Parker` 
and `Douglas` and somewhat longer than those of `Pajaro`. `Oso` plants are 
about the same size as those of `Douglas`; larger than those of `Parker`, 
`Chandler` or `Pajaro` as indicated by petiole length. Bract leaflets 
occur on many of the petioles of `Oso`, somewhat higher up than those of 
`Pajaro`, `Chandler` and `Douglas` and considerably higher up than those 
of `Parker`, 77% vs 57%, respectively. Runner production is very good, 
comparable to that of `Chandler`. Yellow "stripe" or "streak" occurs in 
the leaves occasionally (similar to `Pajaro`) and should be selected 
against in the nursery. 
Isozymes in leaf extracts: `Oso` has been characterized for three enzyme 
systems by starch gel electrophoresis: A. Phosphoglucoisomerase (PGI): B. 
Leucine amino peptidase (LAP); and C. Phosphoglucomutase (PGM). They 
compare with other standard short-day type California cultivars as 
follows: 
TABLE 2 
______________________________________ 
CHAND- - 
OSO DOUGLAS PAJARO LER KER 
______________________________________ 
PGI A2 A3 A4 A1 A4 
LAP B3 B3 B3 B3 B3 
PGM C2 C1 C1 C1 C2 
______________________________________ 
`Oso` can thus be distinguished unambiguously from the five comparison 
cultivars by using only two enzyme systems (PGI and PGM). The `Oso` 
pattern however, is identical to that of California day-neutral `Selva` 
(U.S. Plant Pat. No.5,266). 
Disease and pest reaction: `Oso` is highly resistant to (tolerant of) the 
virus diseases common in California including "Mild Yellow Edge" and 
complexes involving it. It is quite susceptible to common leafspot 
(Ramularia), at least as susceptible as `Chandler` or `Pajaro`, more 
susceptible than `Douglas` or `Parker`. `Oso` is about equal to `Chandler` 
or `Pajaro` in sensitivity to two-spotted mite infestation, a little less 
sensitive than `Parker` and `Douglas`. 
Flowering, fruiting, fruit and production characteristics: `Oso` is a 
standard, facultative short-day type cultivar, subject to modification in 
fruiting response in California as influenced by day-length, growing 
temperature and chilling. Flowers, borne on relatively long peduncles are 
large and attractive with 5 to 7 petals and are completely self-fertile 
with ample pollen throughout the season. Pollination is generally good 
with minimal malformation. The fruit shape is blocky to wedgy medium conic 
and may be somewhat hollow. `Oso` yield and midseason fruit and quality 
characteristics are compared with those of important short-day type 
California cultivars as grown under optimum conditions under the "hill" 
system in winter plantings at the University of California Strawberry 
Research Facility Watsonville in Table 3. 
TABLE 3 
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DOUG- PA- CHAND- - 
OSO LAS JARO LER KER 
______________________________________ 
Yield 2202 1495 1060 1924 1587 
(GR/Plant) 
Size 27.6 27.5 24.8 24.1 25.1 
(GR/Fruit) 
Firmness 
6.2 5.0 5.9 5.7 6.7 
Color 7.5R4.5/ 6R4/12 5R4/12 
5R4/12 7R4.5/13 
11 
Ascorbic 
31.9 27.8 37.7 25.3 25.9 
acid 
Soluble 7.7 7.8 7.7 7.8 7.7 
solids 
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`Oso` is capable of yielding as much or more than the highest yielding 
California cultivars including `Chandler`. Fruit size averages as larger 
or larger than the largest fruited California cultivars, including 
`Douglas`. `Oso` fruit is very firm, almost equal to that of `Parker`, 
much firmer than `Chandler` or `Douglas` as measured by a penetrometer 
equipped with a "Hunter Force Gage" and it handles very well. The fruit 
skin color is similar to that of `Parker` but less red than `Chandler`, 
`Douglas` or `Pajaro`. The finish is particularly bright and attractive. 
The flesh color is about the same as the skin but less intense with a 
distinctly lighter ring around the core. The achenes are medium sized 
(smaller than those of `Douglas`), bright yellow and positioned about even 
with the skin surface. The calyx is medium to large sized, positioned from 
even with the base of the fruit to being borne on or short rather thick 
neck, somewhat reflexed. The ascorbic acid content ranges from about as 
high as `Chandler`, `Douglas` or `Parker` but not as high as for `Pajaro` 
as measured by the Loeffler and Ponting method (1942, J. Indust. and 
Engin. Chem. 14:846). Soluble solids measurements fluctuate well within 
the range of the comparision cultivars. The flavor of `Oso` is very good, 
mild sub-acid, somewhat less sharp than that of `Chandler`. The fruit is 
recommended for fresh market and processing. `Oso` is of interest for both 
winter and summer planting in California and should be tried in all areas.