., 2011 ; Utley et al., 2013 ). In addition to black walnut, colonization of butternut by WTB and infection by G. morbida were reported for the first time in Oregon in 2011 ( Serdani et al., 2013 ). Butternut is also highly susceptible to another
Andrea R. Hefty, Mark V. Coggeshall, Brian H. Aukema, Robert C. Venette, and Steven J. Seybold
Kristen R. Hladun and Lynn S. Adler
hubbard squash ( Cucurbita maxima ) is an effective PTC for the main crop, butternut squash ( C. moschata ), because it is an attractive food source for a major cucurbit pest, the striped cucumber beetle ( Acalymma vittatum F.) ( Andersen and Metcalf
M.E. Ostry and P.M. Pijut
Butternut (Juglans cinerea L.) has many fine qualities as a nut species, however, it has never been commercially important. Although the nut is very edible, only a few cultivars have been selected that have desirable nut size and cracking qualities. In the last 20 years there has been a dramatic decline in the number of butternut in native stands caused to a large extent by the lack of natural reproduction and a damaging canker disease. Evidence suggests that superior, disease resistant trees can be propagated and if isolated from areas where the disease is prevalent, may remain disease-free. It is important that the remaining genetic diversity within the species is maintained. Various butternut conservation practices and research projects to restore butternut populations are underway in the United States and Canada.
Paula M. Pijut
Butternut (Juglans cinerea L.), a native hardwood to the northeastern United States, is a valuable species for its wood and edible nuts. Butternut is becoming endangered in its native range as a result of a virulent fungal (perennial canker) pathogen, Sirococcus clavigignenti - juglandacearum. Micropropagation techniques are being developed to clone disease-resistant specimens. Axillary buds, obtained from 2-3-month old seedlings, were induced to break buds in vitro and form a single shoot when cultured on Murashige and Skoog (MS) medium supplemented with 200 mg/l casein hydrolysate, 3% sucrose, and 2 mg/l 6-benzylaminopurine. Roots were initiated on microshoots when cultured on half-strength MS medium containing 100 mg/l casein hydrolysate, 1.5% sucrose, and 0.5 mg/l indole-3-butyric acid for seven days in the dark. Adventitious roots elongated when shoots were placed in the light on the same medium, but with 2% sucrose, and no growth regulators. Rooted plantlets were successfully acclimated ex vitro. These results provide a basis for the development of techniques to micropropagate selected, mature, disease-resistant butternut germ plasm.
Paula M. Pijut and Melanie J. Barker
Butternut trees are becoming endangered as a result of butternut canker disease; thus, it is desirable to propagate disease-resistant trees for screening and provenance tests. The objective of this study was to determine the conditions necessary for successful cutting propagation. In 1998, 10 trees were selected from a 4-year-old butternut plantation located in Rosemount, Minn. Hardwood cuttings were collected 30 Mar., 21 Apr., and 6 May. The auxins, indole-3-butyric acid-potassium salt (KIBA) in water at 0, 29, or 74 mmol·L-1 were tested for root induction. The basal end of cuttings were dipped in treatment solutions for 10 to 15 s and placed in a 1 peat: 1 perlite mixture in Deepots™ (D40) in a mist bed. Mist was applied for 5 s every 15 min. Greenhouse conditions were: 12-h photoperiod provided by high-pressure sodium lamps (60 μmol·m-2·s-1), 22 °C, and bottom heat of 27 °C (heating pads). Softwood cuttings were collected 20 May, 18 June, 30 June, and 23 July. Rooting treatment solutions and greenhouse conditions were the same as for the hardwood cuttings, except no heating pads were used. Rooted cuttings were planted in Treepots™ (10 × 10 × 36 cm) and gradually hardened off from the mist bed. Hardwood cuttings from the first two collection dates did not initiate roots. Best rooting (12.5%) was achieved on hardwood cuttings collected 6 May using 29 mmol·L-1 KIBA. Softwood cuttings rooted to some degree at all concentrations of rooting solution and at every collection date. The greatest rooting (70%) was achieved using 74 mmol·L-1 IBA. In general, best rooting percentages were achieved with softwood cuttings collected 18 June and 23 July and treated with 62 mmol·L-1 KIBA or 74 mmol·L-1 IBA. Both rooted hardwood and softwood cuttings were successfully acclimatized from the mist bed and many have initiated new growth.
Rachel L. Hultengren, Lindsay Wyatt, and Michael Mazourek
resistance and the lack of options for organic systems highlight the continued need for host resistance as a priority trait in breeding programs ( Pérez-García et al., 2009 ). ‘Honeynut’ is a miniature butternut with exceptional color, high percent soluble
Laura L. Van Eerd
N fertilizer response study in a temperate climate on processing or fresh market butternut squash. There have been only a few N fertilizer studies on large-fruit cucurbitaceous crops ( Bhella and Wilcox, 1989 ; Dweikat and Kostewicz, 1989 ; Goreta
Vuvu D. Manseka and James R. Hicks
Butternut squash was harvested at two stages of maturity in 1994 and was cured for 10 days at 26°C and 80% or 95% relative humidity (RH) before storage in air at 12°C and 65% or 80% RH for 144 days. Fresh weight was assessed right after harvest along with carotene (milligram per 100 grams fresh weight), carbohydrates (milligrams per gram dry weight) and internal color (L, a, b). Percent weight loss and all quality components were assessed immediately after curing and every 48 days thereafter. Weight loss increased with days in storage and was substantially minimized by a humidified environment down to 6%. The 95% curing treatment reduced weight loss to levels below the upper threshold for consumer acceptance (<15%) after 144 days. Maturity at harvest did not affect weight loss during storage, but rather the percent dry weight. Beta-carotene increased by >100% during storage. A positive correlation was established between weight loss and beta-carotene and also between the a value and beta-carotene. Curing at 95% RH obviously reduced beta-carotene content to less than one-third of its corresponding amount in noncured fruit. Sucrose increased as glucose and fructose and starch decreased during storage in cured and noncured fruit. Starch was found to decrease by 26% after 144 days in storage. The lowest levels of starch were found early during storage in fruit cured at 95% RH, but the difference between treatments disappeared by the end of storage.
Paula M. Pijut and Melanie J. Moore
Juglans cinerea L. (butternut) is a hardwood species valued for its wood and edible nuts. Information on the vegetative propagation of this species is currently unavailable. Our objective was to determine the conditions necessary for successful stem-cutting propagation of butternut. In 1999 and 2000, 10 trees (each year) were randomly selected from a 5- and 6-year-old butternut plantation located in Rosemount, Minn. Hardwood stem cuttings were collected in March, April, and May. Softwood cuttings were collected in June and July. K-IBA at 0, 29, or 62 mm in water and IBA at 0, 34, or 74 mm in 70% ethanol were tested for root induction on cuttings. The basal end of cuttings were dipped in a treatment solution for 10 to 15 seconds, potted in a peat: perlite mixture, and placed in a mist bed for 5 to 8 weeks. Rooted cuttings were gradually hardened off from the mist bed, allowed to initiate new growth, over-wintered in a controlled cold-storage environment, and then outplanted to the field. For hardwood cuttings, rooting was greatest for those taken in mid-May (branches flushed out), 22% with 62 mm K-IBA and 28% with 74 mm IBA. Softwood cuttings rooted best when taken in June (current season's first flush of new growth or softwood growth 40 cm or greater) and treated with 62 mm K-IBA (77%) or 74 mm IBA (88%). For 1999, 31 out of 51 rooted softwood cuttings (60.8%) survived overwintering in cold storage and acclimatization to the field. For 2000, 173 out of 186 rooted softwood cuttings (93%) survived overwintering and acclimatization to the field. Chemical names used: indole-3-butyric acid-potassium salt (K-IBA); indole-3-butyric acid (IBA).
Matthew T. Rulevich, Francis X. Mangan, and Anne K. Carter
Field studies were conducted in 1998 and 1999 in Massachusetts to assess the effects of transplants, black polyethylene mulch, and polyester spun-bonded row cover on early fruit set and total yield of two squash (Cucurbita moschata Duchesne) cultivars: `C42 × La Segunda' calabaza and `Waltham' butternut. Treatment comparisons included direct-seeded or transplanted squash, with or without black polyethylene mulch, and with or without the addition of a row cover in all combinations. The use of transplants was more effective at stimulating early fruit set and highest total yield than the use of mulch and row cover. The initiation of fruit set using transplants was advanced 9 days relative to direct-seeding. Mulch and row cover treatments significantly advanced early fruit set by 7 and 5 days, respectively, but only in 1998. Yields for both winter squash were 45% higher using transplants compared to direct seeding, 19% higher using mulch compared to bare soil, and 16% higher using row cover compared to no row cover. Total yields were higher for both cultivars in 1999 (warm, dry season) than in 1998 (cool, wet season). Use of transplants with plastic and row cover compared to the use of direct seed with neither plastic nor row cover increased yield of calabaza by 100% in both 1998 and 1999. Only the direct seeded plus plastic plus row cover treatment had yields that were similar to any of the transplanted treatments. Transplant treatments also increased number of fruit per plant and fruit size for both calabaza and butternut.