., 2004 ). Bare-root transplants are affordable to growers, but usually vary in crown size and overall quality ( Bish et al., 2000 ). Once bare-root transplants are shipped, a high proportion of roots become unable to take up water and nutrients, due to
are cultivated for food as immature fruit (summer squash) and mature fruit (winter squash and processing pumpkins), and they are also grown for fall decorations, such as jack-o’-lanterns and gourds ( Paris, 2016 ). Phytophthora crown and root rot
Thermotolerance of pineapple crowns (`Champaka 153') to 50C and above was increased with a 30-min first treatment at 30, 35, or 40C. Pineapple crowns receiving a 30-min heat treatment, before a second heat treatment at 50 or 55C, exhibited significantly less leaf damage than controls receiving no first treatments (P ≤ 0.05). The degree of thermotolerance was dependent upon the season in which crowns were harvested; greater thermotolerance occurred in crowns harvested in April than those harvested in October. Maximum thermotolerance occurred after an interval of at least 8 h between the first treatment and the higher temperature heat treatment. Thermotolerance was stable for at least 24 h.
cultivars and rootstocks and differ in their use of plant protection products, we used the same approach as that already found in tree pruning handbooks and show only the most common tree responses in the form of changes in tree crown structure without
Larvae of several insects injure and kill strawberry (Fragaria ×ananassa Duchesne) plants by burrowing into and hollowing out plant crowns. Occasionally, these infestations are serious enough to cause heavy economic losses to fruit producers and nursery plant growers. In 1997 in Beltsville, Md., we observed wilting and dying mature plants and unrooted runner plants in two experimental strawberry plantings. Injury by larvae was extensive; large cavities occurred in crowns, and the central pith tissues were removed from stolons and leaf petioles. Often, insect frass was seen at entrance holes. Larvae removed from hollowed-out parts of injured plants were identified as the European corn borer (Ostrinia nubilalis Hübner) in their fifth instar stage. Their presence in this instance also was associated with a cover crop of millet [Setaria italica (L.) P. Beauv., `German Strain R'] planted between the strawberry rows for weed suppression. This is the first published report of the European corn borer attacking strawberry. Although this insect may occur only sporadically in strawberry plantings, it may become important in the future. Growers and other professionals should become aware of this new strawberry pest and recognize that its management in strawberry will be different from management of other crown-boring insects.
Fusarium crown and stem rot, caused by Fusarium avenaceum (Fr.: Fr.) Sacc., is a serious disease of lisianthus [Eustoma grandiflorum Raf. (Shinn.)]. While more than 80 new cultivars of lisianthus have been released for sale in the United States in the last decade, there is a lack of information on their susceptibility to this pathogen. Forty-six cultivars of lisianthus were evaluated for their response to infection by F. avenaceum. Cultivars were grouped according to blue/purple, pink, or white flower colors and evaluated within their color class. Although some plants of all cultivars were susceptible to F. avenaceum, partial resistance was observed as indicated by differences in the length of time to symptom expression and in the frequency of diseased plants within each color group. In 21 of the 46 cultivars, 80 to 100% of the plants expressed symptoms within 55 days after inoculation. The lowest frequencies of diseased plants 55 days after inoculation were found in `Ventura Deep Blue' and `Hallelujah Purple' (25%), `Bridal Pink' (23%), and `Heidi Pure White' (53%) for the blue/purple, pink, and white flower color groups, respectively. Screening cultivars for resistance to F. avenaceum is the first step in breeding resistant cultivars. The methods we developed for these studies should be useful in screening for resistance. These results also may help growers select cultivars that are less susceptible to F. avenaceum, which should aid in the management of this disease.
A variety of techniques and vegetative materials are used to asexually propagate blackberry. Blackberry plants can be easily reproduced from root suckers, crown division, root cuttings, tip layering, soft stem cuttings, and tissue culture (TC
block design with four replications. The whole-plot treatments were randomized and consisted of three biodegradable mulch products: BioAgri, Crown 1, and SB-PLA-11 ( Table 1 ). Two subplot soil treatments, mulched and bare ground, were applied in the
floral primordia in eastern thornless blackberry (e.g., ‘Triple Crown’) are not visible until spring ( Takeda et al., 2002 ; Takeda and Wisniewski, 1989 ). The presence of an actively growing shoot tip is necessary during the first 3 or 4 d after the