Blackberry plant named ‘thunderhead’

Abstract

A new and distinct blackberry cultivar that originated from seed produced from a cross between the thorny primocane-fruiting maternal blackberry plant ORUS 4355-2 and the thornless primocane-fruiting paternal blackberry plant ‘Prime-Ark® Freedom’. ‘Thunderhead’ is the first primocane-fruiting blackberry variety released by the USDA-ARS breeding program in Oregon. This new blackberry cultivar can be distinguished by its exceptionally high plant vigor and yields of medium sized berries with high gloss, firmness, excellent flavor and fruit quality, and relatively small seed size. The berries are well suited for fresh eating, with good sweetness and gloss when picked firm, and low bitter notes. The new and distinct blackberry variety contains a genetic background derived from eastern U.S. germplasm and is expected to grow and is expected to perform well in most areas where primocane-fruiting blackberries are currently grown.

Claims

1. A new and distinct cultivar of blackberry plant named ‘Thunderhead’, substantially as illustrated and described, characterized by its plant vigor, and exceptional yields of medium sized berries with excellent fresh eating quality, firmness, and flavor, with small seed size.

Description

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

(1) This new blackberry plant is illustrated by the accompanying photographs that show the plants, ripening fruit morphology, and harvested fruit; the colors shown are as true as can be reasonably obtained by conventional photographic procedures.

(2) FIG. 1 shows an example of a fruiting cluster with ripe ‘Thunderhead’ fruit.

(3) FIG. 2 shows a close-up example of the size and shape of ‘Thunderhead’ fruit.

(4) FIG. 3 shows a clamshell of ‘Thunderhead’ fruit (left) and ‘Prime-Ark 45’ fruit (right) after 23 days of refrigerated storage at ˜4° C.

(5) FIG. 4 shows a flat of freshly harvested ‘Thunderhead’ fruit.

(6) FIG. 5 shows a 2 year old plot of entire ‘Thunderhead’ plants during flowering in late July.

(7) FIG. 6 shows the morphology of ‘Thunderhead’ flowers.

DETAILED DESCRIPTION OF THE NEW CULTIVAR

(8) The following description of ‘Thunderhead’ is based on observations taken from 2016 to 2021 growing seasons in trials in Corvallis and Aurora, Oreg. This description is in accordance with UPOV terminology. Color designations, color descriptions and other phenotypical descriptions may deviate from the stated values and descriptions depending upon variation in environmental, seasonal, climatic, and cultural conditions. ‘Thunderhead’ has not been observed under all possible environmental conditions. Color terminology follows The Royal Horticultural Society Colour Chart. London (R.H.S.) (5.sup.th edition, 2007).

(9) Table 1 shows plant characteristics of the new cultivar. Characteristics include plant vigor, growth habit, date of bud-break, presence of spines further than 0.6 m from the soil surface, presence of spines less than 0.6 m from the soil surface, weight of primary fruit, uniformity of berry shape, fruit firmness, fruit flavor, fruit soluble solids (%; in Brix), fruit pH, fruit titratable acidity (% as citric acid), and yield (actual kg⋅plt−1). Fruit measurements are from 2020 trial data collected from OSU-NWREC (Aurora, Oreg.).

(10) TABLE-US-00001 TABLE 1 Characteristic Thunderhead Prime-Ark ® 45 Plant vigor Very High High Growth habit Erect/Primocane- Erect/Primocane- fruiting fruiting Date of budbreak Week 3, Week 2, March (2021) March (2021) Presence of spines further Low-Moderate Moderate than 0.6 m from the soil surface Presence of spines less Moderate Moderate than 0.6 m from the soil surface Weight of primary fruit 8.2-10.4 g 11.0 g Uniformity of berry shape Good Good Fruit firmness Very good Very good Fruit flavor Very good Good Fruit gloss Very good Good Texture of fruit when Very good Moderate chewed Drupelet skin resistance to Very good Good abrasion Fruit soluble solids (%; in 15.08 15.87 Brix) Fruit pH 3.52 3.40 Fruit titratable acidity (% 11.00 1.33 as citric acid) Yield (actual kg .Math. plt-1) 8.32 5.25

(11) Table 2 shows floricane and mature primocane characteristics of the new cultivar. Characteristics include diameter at base, diameter at midpoint, diameter at terminus, internode length at base, internode length at midpoint, internode length at terminus, presence of spines further than 0.6 m from the soil surface, presence of spines less than 0.6 m from the soil surface, floricane color at base, floricane color at midpoint, floricane color at terminus, floricane lateral length, floricane lateral strength, primocane color at base, primocane color at midpoint, primocane color at terminus, and floricane length (range).

(12) TABLE-US-00002 TABLE 2 Characteristic Thunderhead Diameter at base 1.65 cm Diameter at midpoint 1.24 cm Diameter at terminus 0.31 cm Internode length at base 5.85 cm Internode length at midpoint 5.81 cm Internode length at terminus 2.37 cm Presence of spines further than Low-Moderate 0.6 m from the soil surface Presence of spines less than 0.6 m Moderate from the soil surface Attitude of spine in relation to the Outwards cane Floricane color at base NA (primocane type) Floricane color at midpoint NA (primocane type) Floricane color at terminus NA (primocane type) Floricane lateral length NA (primocane type) Floricane lateral strength NA (primocane type) Primocane color at base RHS 187B Primocane color at midpoint RHS 145A Primocane color at terminus RHA 183A Floricane length (range) NA (primocane type)

(13) Table 3 shows primocane foliage characteristics of the new cultivar. Primocane characteristics include mature compound leaf width, mature compound leaf length, number of leaflets per primocane compound leaf, mature leaflet shape, mature leaflet apex, mature leaflet base, mature terminal leaflet width, mature terminal leaflet length, mature first lateral leaflet width, mature first lateral leaflet length, leaflet margin, leaflet serration teeth length, leaflet serration teeth width at base, spine presence on leaves, pubescence on primocane leaflet: upper surface, pubescence on primocane leaflet: undersurface, primocane leaf color abaxial, primocane leaf color adaxial, petiole length, petiole color: upper surface, petiole color: undersurface, petiolule length: terminal leaflet, petiolule length: first distal leaflet, petiolule color: abaxial, petiolule color: adaxial, stipule length, and stipule width.

(14) TABLE-US-00003 TABLE 3 Characteristic Thunderhead Mature compound leaf width 15.35 cm Mature compound leaf length 16.12 cm Number of leaflets per primocane Usually 3-5 compound leaf Mature leaflet shape Ovate to round Mature leaflet apex Acuminate abruptly Mature leaflet base Cordate Mature terminal leaflet width 5.97 cm Mature terminal leaflet length 7.58 cm Mature first lateral leaflet width 5.57 cm Mature first lateral leaflet length 7.07 cm Leaflet margin Serrate Leaflet serration teeth length 0.80 cm Leaflet serration teeth width at 0.63 cm base Spine presence on leaves Absent or few Pubescence on primocane leaflet: Light/sparse upper surface Pubescence on primocane leaflet: Light/even undersurface Primocane leaf color abaxial RHS 146B Primocane leaf color adaxial RHA 146A Petiole length 7.95 cm Petiole color: upper surface RHS 149A Petiole color: undersurface RHS 185A Petiolule length: terminal leaflet 26.30 cm Petiolule length: first distal leaflet 19.76 cm Petiolule color: abaxial RHS 60C Petiolule color: adaxial RHS 150B Stipule length 1.48 cm Stipule width 0.68 cm

(15) Table 4 shows flower and flowering characteristics of the new cultivar. Flower and flowering characteristics include date 1st bloom, date full bloom, date last bloom, petal color, number flowers per cluster, number of petals per flower, flower diameter, petal length, petal width, and number of sepals per flower.

(16) TABLE-US-00004 TABLE 4 Characteristic Thunderhead Date 1.sup.st bloom 10-July Date full bloom 24-July Date last bloom 24-August Petal color RHS 155D Number flowers per cluster 18.00 Number of petals per flower 7-10 Flower diameter 3.68 cm Petal length 1.68 cm Petal width 1.24 cm Number of sepals per flower 5-6 Peduncle length (cm) 4.68 Rachis length (cm) 11.47 Peduncle color RHS 60B Cyme type Elongate simple cyme

(17) Table 5 shows fruit and fruiting characteristics of the new cultivar. Fruit and fruiting characteristics include date 5% of fruit were ripe, date 50% of fruit were ripe, date 95% of fruit were ripe, weight of primary fruit, weight of secondary fruit, weight of tertiary fruit, diameter of primary fruit at equator, diameter of 2° fruit at equator, diameter of 3° fruit at equator, diameter of 1° fruit at poles: tip, diameter of 1° fruit at poles: base, diameter of 2° fruit at poles: tip, diameter of 2° fruit at poles: base, diameter of 3° fruit at poles: tip, diameter of 3° fruit at poles: base, berry length primary fruit, berry length 2° fruit, berry length 3° fruit, ratio of primary fruit length to width, shape description, uniformity of berry shape, color when full ripe, number of drupelets per fruit, individual seed weight, glossiness, firmness, flavor, texture of fruit when chewed, drupelet skin resistance to abrasion, ease of separation of fruit from pedicel, machine harvestability, resistance to heat damage of fruit, berries per inflorescence—mean, berries per inflorescence range, soluble solids (%; in Brix), pH, titratable acidity (% as citric acid), and yield (actual kg⋅plt−1). Fruit chemistry data is from 2020 field season at OSU-NWREC.

(18) TABLE-US-00005 TABLE 5 Characteristic Thunderhead Date 5% of fruit were ripe 14-August Date 50% of fruit were ripe 10-September Date 95% of fruit were ripe Fruits until first Fall frost Fruiting lateral length 20-40 cm Weight of primary fruit 10.40 g Weight of secondary fruit 7.27 g Weight of tertiary fruit 5.95 g Diameter of primary fruit at equator 2.28 cm Diameter of 2° fruit at equator 2.05 cm Diameter of 3° fruit at equator 1.98 cm Diameter of 1° fruit at poles: tip 1.51 cm Diameter of 1° fruit at poles: base 2.16 cm Diameter of 2° fruit at poles: tip 1.30 cm Diameter of 2° fruit at poles: base 1.87 cm Diameter of 3° fruit at poles: tip 1.19 cm Diameter of 3° fruit at poles: base 1.95 cm Druplets size Small to medium Berry length primary fruit 3.48 cm Berry length 2° fruit 2.94 cm Berry length 3° fruit 2.71 cm Ratio of primary fruit length to 1.54 width Shape description Blocky to conical Uniformity of berry shape Medium Color when full ripe RHS 203B Number of drupelets per fruit 157 Individual seed weight 2.61 mg Glossiness Medium to high Firmness Very firm Flavor Very good Texture of fruit when chewed Very good Drupelet skin resistance to abrasion Excellent Ease of separation of fruit from Very easy pedicel Machine harvestability NA (only picked fresh) Resistance to heat damage of fruit Very good Berries per inflorescence - mean 12 Berries per inflorescence range 8-15 Soluble solids (%; in Brix) 15.08 pH 3.52 Titratable acidity (% as citric acid) 11.00 Yield (actual kg .Math. plt-1) 8.32

COMPARISON WITH PARENTAL AND COMMERCIAL VARIETIES

(19) ‘Thunderhead’ differs from the female parent blackberry plant ORUS 4355-2 in that it has a more vigorous plant with significantly greater yields. The fruit are slightly smaller than ORUS 4355-2, but it produces larger numbers with a higher number of fruits per lateral. The ‘Thunderhead’ fruit quality is improved with robust firmness and flavor and appears less susceptible to mold and red berry mite (RBM).

(20) ‘Thunderhead’ differs from the male parent blackberry plant ‘Prime-Ark® Freedom’ in that it lacks complete genetic thornlessness, shows higher yields and plant vigor, and produces larger numbers of smaller-sized berries with a more consistent/uniform shape and a smaller, more uniform drupelet size. The ‘Thunderhead’ flavor is less astringent when grown in Oregon.

(21) ‘Thunderhead’ differs from the primocane-fruiting blackberry variety ‘Prime-Ark® 45’ in that it has shown higher fruit yields within a similar ripening season/window when grown in Aurora, Oreg. The ‘Thunderhead’ fruit are slightly smaller, with smaller individual drupelet size and somewhat higher drupelet uniformity. The fruit were similarly glossy and sweet to ‘Prime-Ark® 45’, with a similar shelf life and post-harvest appearance after 23 days in refrigerated storage in plastic clam shell packaging at 4° C. The ‘Thunderhead’ fruit contain slightly lower bitter notes than ‘Prime-Ark® 45’, and smaller less noticeable seeds.