Flowers are harvested with sharp knives or electric pruning shear. On standard carnations two to three nodes and on spray carnations three to four nodes are left on the shoots for the next flowering. Flowers should be cut in the early morning when plants are turgid. Standard carnations are harvested as open flowers or in the bud stage. Spray carnations are harvested with two flowers open and the rest showing color. Flowers are handled carefully to avoid breakage and bruising. It is important to expose flowers to a 40° to 48°F environment as soon as possible to reduce plant temperature. Precooling the flowers maintains quality and increases longevity.
Above all else, investment in a pair of high-quality pruning shears is mandatory. One manufacturer even has a special hand grip designed for left-handed people, swivel handles and a model with blade removal for maintenance. For miniature roses, there are smaller versions of these pruning shears which rely on a smaller, straight-edged blade surface. For removal of large woody canes at the bud union, a pruning saw will allow access for flush removal. Attempts to use pruning shears for these jobs usually result in damage to the bud union. It is best to approach cane removal with a proper saw designed specifically for the job. For cutting large-diameter canes a pair of lopping shears with 30- or 45-cm handles can facilitate the cutting without placing too much pressure on the hands. Again, attempts to cut large-diameter canes with pruning shears will require a lot of extra strength. Lopping shears with long handles solve the strength problem and make the cut clean and sharp. Invest in a small wire brush (about 5 cm wide by 75 cm deep) to help remove loose bark from the bud union. Such treatments can often encourage basal breaks and stimulate new growth since growth often finds it impossible to break through the heavy tree-like bark encountered on older bushes. Finally, save on profanities while pruning by buying a good strong pair of leather gauntlet gloves or hand gloves that are puncture-proof. There is nothing as irritating as a thorn under the nail to cause a string of words rarely heard in a rose garden!
Harvesting is done manually when the capsules are dry at the ends of the branches. Pruning shears are used to cut branches and also remove inflorescence containing 15–20 capsular fruits. Once harvested, the fruit are carried in baskets to a land or a warehouse where, after drying, they will be processed in specific equipments or manually. The machines separate the capsules from the seeds and classify them for subsequent packing in polyethylene bags, where they remain preserved for more than five years in perfect condition without any plant protection treatment (Cruz et al., 2008).
Human beings disseminate all kinds of pathogens over short and long distances in a variety of ways. Within a field, humans disseminate some pathogens, such as tobacco mosaic virus, through the successive handling of diseased and healthy plants. Other pathogens are disseminated through tools, such as portable mini electric garden shears, contaminated when used on diseased plants (e.g., pear infected with fire blight bacteria), and then carried to healthy plants. Humans also disseminate pathogens by transporting contaminated soil on their feet or equipment, using contaminated containers, and using infected transplants, seed, nursery stock, and budwood as mentioned previously. Finally, humans disseminate pathogens by importing new varieties into an area that may carry pathogens that have gone undetected, by traveling throughout the world, and by importing food or other items that may carry harmful plant pathogens. Examples of the role of humans as a vector of pathogens can be seen in the introduction into the United States of the fungi causing Dutch elm disease and white pine blister rust and of the citrus canker bacterium, in the introduction in Europe of the powdery and downy mildews of grape, and, more recently, in the rapid spread of sorghum ergot almost throughout the world (Fig. 2-20).
The primary fungi of an ambrosia beetle are abundant in a gallery only when larval stages are present (Kajimura and Hijli 1992). Thus, the best isolates of primary fungal symbionts can be made a month or two after initial infestation. Galleries are exposed by sawing thin sections from the infested bole. It is important to work as quickly and as aseptically as possible, using alcohol-flamed saws, wood chisels, and/or pruning shears. Adult insects can be removed, and visible fungal growth within the several-millimeter-diameter gallery can be isolated using sterile fine forceps. Thin slices or chips of galleries should be preserved, dried, and mounted, or mounted directly on slides with fixative mounting medium, such as lactophenolaniline blue, for later study.
Ambrosia fungi in the genus Corthylus and most Xyleborus species generally form a thick, whitish palisade layer on the walls of galleries if eggs and/or larvae are present. That fungal growth can be isolated easily by streaking or spot plating on isolation media (see next section on “Culture”).
Fungal growth usually is not so evident on the gallery walls or larval cradles of xylomycetophagous insects; thus, small slices and chips of wood should be removed aseptically for plating. Slices or fragments of galleries can be placed aseptically in a sterile moist chamber (Appendix I) to encourage fungal growth in the absence of actively feeding larvae, so that primary ambrosia fungi can be isolated, often within a few days, before contamination from saprobic fungi.
Live beetles trapped in flight or taken from galleries are difficult to handle because of their small size and smooth cylindrical shape. A simple vacuum apparatus consisting of a sterile micropipette tip with a small aperture attached to a rubber hose fixed to a vacuum pump or vacuum line allows one to pick up individual beetles and transfer them easily from dish to dish or to sterile glass slides for dissection.
Beetles can be surface disinfected to reduce the presence of nonmycangial microbes by washing in sterile 0.1% HgCl2 solution or dilute sterile bleach (NaHCl2) for 2–4 minutes, followed by several rinses in sterile water. Investigators can also free adult beetles of external nonmycangial microbes by placing them alternately in plates of sterile wet filter paper for 18 hours and then on dry sterile filter paper for 6 hours. Several transfers typically remove most external microbes. Individual beetles can be stored on sterile moist filter plates for months at refrigerator temperature until needed for dissection and isolation. Prevention of dehydration appears to be the critical factor for keeping them alive during long-term storage.
The process of harvesting in Stevia is very important to obtain the highest leaf biomass yield with the most desirable quality and quantity of the sweet compound of steviol glycosides with a desirable taste. The time to harvest Stevia crop varies dependent on the place and time. The first harvest generally can be done 4 months after cultivation and the subsequent harvest is suggested to be done once every 3 months or 40–60 days later. Generally, three commercial harvests can be done every year. Optimum biomass and steviol glycoside quality and quantity can be obtained at the stage of flower bud initiation. It is suggested to cut the branches about 5.0 cm above the ground with tree branches powered pruning shears before stripping the leaves. As the tips of the stems contain as much steviol glycoside as the leaves, they can be added to the harvest yield. It is recommended to cut the stems leaving about a 10 cm portion above the ground to induce the emergence of new flushes, for the subsequent harvest (Kassahun et al., 2013). Benhmimou et al. (2017) reported that the optimal yield depended on the harvesting time and the yield of summer harvesting (August) was higher than that of autumn harvesting (October).
One of the important processes after crop harvesting is drying the Stevia leaves in the best way. The herb should be immediately dried after harvesting by placing on a net or screen. The plants can be dried in full sun, shade, or by passing hot dry air over the plant leaves. This drying process with heat lasts for 24–48 h to obtain completely dry leaves at 40°C–50°C. It should be noted that excessive heat or longer drying time could lower the stevioside level of dried leaves. A dehydrator machine can also be used to dry the Stevia leaves (Singh et al., 2014; Zewdinesh et al., 2014). Samsudin and Aziz (2013) reported that the quality of Stevia leaves dried in a hot air dryer at 50°C temperature for 6 h was better in terms of sweetness, nutrient content, and color of leaves. After applying any of the drying methods, the dry leaves should be packed and stored in a dry and cool place for further utilization (Zewdinesh et al., 2014).
Azaleas are pinched to increase shoot numbers, plant size, floriferousness, and also as a mechanism for timing flowering. The first mentioned reasons will be discussed in this section on vegetative development, while the use of pinching to schedule flowering will be considered in the section on flowering.
The final size of azalea plants will be largely determined by the number of times plants are pinched, if growing conditions are satisfactory. In many places, azaleas are only pinched once each year, but the plants could be pinched every 3 to 4 months if faster increases in size were desired. This can only be done under protected conditions or in climates where low temperatures are not encountered. The expenses encountered in indoor culture must be considered, but new vegetative growth could always be occurring under the proper environmental conditions. A night temperature of 65°F and long days will enhance vegetative growth. Fertilization programs would have to be more precise than under conditions where plants are only pinched once annually. Carbon dioxide injection has also been suggested for maximum growth.
Pinching can be done manually or chemically, but most plants are pinched with powerful battery operated pruning shears or electric clippers. Some propagators use the pinch as a way to get cuttings so the plants serve dual roles as stock plants and eventually as flowering plants. If such a practice is followed then the pinch involves the removal of shoots about 3 to 4 inches long. If cutting production is not an objective of pinching, then only the tips of the shoots need to be removed. More leaf axils then remain, so one might expect more lateral shoots than when a harder pinch is made.
There are different chemicals that have been used to pinch azaleas. The fact that azaleas are multibranched plants makes chemical pinching worthwhile. Fields of azaleas that might require weeks to be pinched can be chemically pinched in hours, so labor costs are significantly reduced. The crop will be more uniform in development as well, as all plants are pinched at the same time.
Off-Shoot-O was the first chemical pinching agent of economic importance (Stuart, 1967, 1975) but its use has declined. Effectiveness of Off-Shoot-O is influenced by temperature, relative humidity, stage of apex development, and cultivar. The chemical works by physically damaging the apex, and the material has to come in contact with the apex for pinching to occur. One can tell within about 24 hours if shoot tip damage has occurred.
Dikegulac (Atrimmec) was the second prominent chemical pinching agent. Its mode of action is biochemical, so the chemical does not have to come in direct contact with the apex. The material is translocated through the phloem, and DNA synthesis is affected (Bocion et al., 1975; de Silva et al., 1976). It is not affected as much by the factors that influence the effectiveness of Off-Shoot-O (Larson, 1978). The effectiveness of Atrimmec cannot be determined until at least 2 weeks after its application. Lateral shoot initiation and development are delayed compared to those on plants that are manually pinched, and new leaves are often very narrow. Some azalea growers do not use Atrimmec alone, but prune the large, long shoots to get the desired plant shape, break apical dominance, and then apply Atrimmec 2 days later to stimulate lateral branching.
Other new chemicals are being tried, but EPA label clearance is lacking at this time.
Every mycologist has his or her preferred collecting paraphernalia, and to a degree preferences depend on the taxa being collected. At least four items are required for collecting macrofungi: (1) a tool for cutting and digging, (2) a container or wrapping material for each specimen, (3) a larger container for transporting specimens in the field and back to the lab, and (4) a label for each specimen.
A thick-bladed, moderately sharp knife can be used to cut woody substrata or dig in soil. Some collectors carry both a knife and a trowel for collecting sporocarps from soil. Different types of fungi occurring on wood require different types of collecting equipment. An ax or hatchet often is needed to extract wood to a depth sufficient to enable identification of the host if it is unknown. However, a mallet and wood chisel, a heavy sheath knife, or a folding knife with a locking blade are usually sufficient for removing the fungus. A pair of electric bypass pruning shears and a folding pruning saw are also helpful for cutting smaller diameter twigs and branches to a uniform length. Care must be used to avoid undue damage to the plant if collecting from a living tree (Figs. 8.10 and 8.11).
- Creado: 18-09-21
- Última sesión: 18-09-21