By making the pruning cuts in a certain order, the total number of cuts is reduced greatly. The skilled pruner first removes all dead, broken, diseased or problem limbs by cutting them at the point of origin or back to a strong lateral branch or shoot.
Often, removing this material opens the canopy sufficiently so that no further pruning is necessary. The next step in pruning is to make any training cuts needed. By cutting back lateral branches, the tree or shrub is trained to develop a desired shape, to fill in an open area caused by storm or wind damage or to keep it in bounds to fit a given area.
To properly train a plant, one should understand its natural growth habit. Always avoid destroying the natural shape or growth habit when pruning unless maintaining a close watch over the plant, for after a period of time it attempts to assume the more natural growth habit.
Make additional corrective prunings to eliminate weak or narrow crotches and remove the less desirable central leader where double leaders occur. After these cuts have been made, stand back and take a look at your work. Are there any other corrective pruning cuts necessary? If the amount of wood removed is considerable, further pruning may need to be delayed a year or so.
Remove water sprouts unless needed to fill a hole or to shade a large limb until other branches develop. Pruning can actually be done at any time of the year; however, recommended times vary with different plants.
Contrary to popular belief, pruning at the wrong time of the year does not kill plants, but continual improper pruning results in damaged or weakened plants.
Do not prune at the convenience of the pruner, but rather when it results in the least damage to the plant. There is little chance of damaging the plant if this rule is followed. In general, the best time to prune most plants is during late winter or early spring before growth begins. There are exceptions to this rule, and they will be noted under the discussion of the specific plant groups.
The least desirable time is immediately after new growth develops in the spring. A great amount of food stored in roots and stems is used in developing new growth. This food should be replaced by new foliage before it is removed; if not, considerable dwarfing of the plant may occur. This is a common problem encountered in pruning. It also is advisable to limit the amount of pruning done late in summer as new growth may be encouraged on some plants.
This growth may not have sufficient time to harden off before cold weather arrives resulting in cold damage or winter kill. Prune plants damaged by storms or vandalism or ones with dead limbs as soon as possible to avoid additional insect and disease problems that may develop. To know and practice the rules of pruning is most important, but of equal importance is using the correct tools. Equipment can be limited to a few items if the proper ones are selected.
Select tools that will do the job, keep a sharp edge, and are relatively easy to sharpen and handle. Some of the most commonly used pruning tools are shown in this section. Good equipment properly cared for does a better job and lasts longer.
Store equipment in a dry room, keep it sharp and in good operating condition. When pruning diseased plants, disinfect all shears and saw blades after each cut to prevent spreading disease to healthy plants.
An example of this is pruning fire blight from pears, pyracantha or cotoneaster. Use alcohol or bleach to disinfect equipment between each cut when pruning diseased plants. Mix at the rate of one part bleach to nine parts water. At the end of the day, oil the pruning equipment well to avoid rusting. There are many kinds of hand pruning shears. Two common styles of hand shears are the scissor action and the anvil cut. In scissor action shears, a thin, sharp blade slides closely past a thicker but also sharp blade.
These usually cost more but make cleaner, closer cuts. In anvil cut shears, a sharpened blade cuts against a broad, flat blade. Lopping shears loppers have long handles that are operated by both hands Figure 1. Better ones can slice through branches of 2 inches or more, depending on species i.
Pole pruners usually have a cutter with one hooked blade above and a cutting blade beneath, similar to a large pair of lopping shears. The cutter is on a pole and is operated by pulling a rope downward. Poles can be made of several materials and can either be in sections that fit together or that telescope. Wooden poles are sturdy but heavy, while aluminum poles are light but can conduct electricity if they touch an overhead electrical wire.
Fiberglass or some type of plastic compound is probably the best pole material. Poles can be fitted with saws, but these are usually very frustrating to use Figure 2. Use of pole pruners can be dangerous. Material cut overhead can fall on the operator unless it hangs up in other branches.
The user should exercise caution and wear head and eye protection. Hedge shears are used mainly for shearing plants into hedges or formal shapes. The most common type is manually operated; however, if large areas of hedges are involved, power-driven shears may be more practical Figure 3. Pruning saws, both rigid or folding, are very useful for cutting larger branches that are too large for hand shears.
Tree saws are available for removing large tree branches. The teeth in these saws are set for a wider cut allowing the sawdust to kick out resulting in less binding in green wood. Bow saws are good only where no obstructions exist for a foot or more above the area to be cut Figure 4. Gas powered and electrical chain saws come in a variety of sizes. They are best suited for removing trees and cutting firewood, but can also be used to prune live plant material.
Only professional arborists should use power saws for pruning up in trees because of safety concerns. Other tools, which are sometimes necessary, are chisels, gouges, pruning knives and mallets.
These all come in handy when repairing storm damage wounds or other wounds. Clean and oil tools regularly, including wiping an oily cloth on blades and other metal surfaces. Keep cutting edges sharp; several passes with a good oil stone will usually suffice. Paint, varnish or regularly treat wooden handles with linseed oil. Use tools properly.
Keep the branch to be cut as deeply in the jaws and near the pivot as possible. Much has been written about the advantages and disadvantages of using a wound dressing on large cuts. Traditionally, wound dressing or pruning paint is used only on cuts larger than an inch in diameter. However, scientists have found that wound dressings are strictly cosmetic and have little to do with preventing insect or disease damage to the wound area. Pruning paint may, in fact, slow down the healing process.
In general, wound dressings are not recommended or necessary, with one exception. On oak trees in areas of Texas where the oak wilt disease is prevalent, wound dressing should be used to help prevent the bark beetle from spreading the disease through the pruned surface on a tree.
To encourage rapid healing of wounds, make all cuts clean and smooth. This requires good, sharp pruning equipment. Do not leave stubs since they are usually where die back occurs. Avoid tearing the bark when removing large branches. The following provides some specifics on pruning techniques. Most woody plants fall into two categories based on the arrangement of the buds on the twigs and branches.
Buds may have an alternate or an opposite arrangement on the twigs. A plant with alternate buds usually is rounded, pyramidal, inverted pyramidal, or columnar in shape. Plants having opposite buds rarely assume any form other than that of a rounded tree or shrub with a rounded crown. The position of the last pair of buds always determines the direction in which the new shoot will grow.
Buds on top of the twig probably will grow upward at an angle and to the side on which it is directed. In most instances, it is advisable to cut back each stem to a bud or branch. Selected buds that point to the outside of the plant are more desirable than buds pointing to the inside. By cutting to an outside bud, the new shoots will not grow through the interior of the plants or crisscross. When cutting back to an intersecting lateral branch, choose a branch that forms an angle of no more than 45 degrees with the branch to be removed Figure 5.
Also, the branch that you cut back to should have a diameter of at least half that of the branch to be removed. Make slanting cuts when removing limbs that grow upward; this prevents water from collecting in the cut and expedites healing. If the cut is too close to the bud, the bud usually dies. If the cut is too far from the bud, the wood above the bud usually dies, causing dead tips on the end of the branches.
When the pruning cut is made, the bud or buds nearest to the cut usually produce the new growing point. When a terminal is removed, the nearest side buds grow much more than they normally would, and the bud nearest the pruning cut becomes the new terminal.
If more side branching is desired, remove the tips of all limbs. The strength and vigor of the new shoot is often directly proportioned to the amount that the stem is pruned back since the roots are not reduced. For example, if the deciduous shrub is pruned to 1 foot from the ground, the new growth will be vigorous with few flowers the first year. However, if only the tips of the old growth are removed, most of the previous branches are still there and new growth is shorter and less vigorous.
Flowers will be more plentiful although smaller. Thus, if a larger number of small flowers and fruits are desired, prune lightly. The burning of the kerosene in the heaters produced a molecule similar to ethylene that synchronized the ripening of the tomatoes!
The formation of ethylene requires oxygen, and the agricultural industry has used this tidbit of information to their advantage. If you control the partial pressure of oxygen and carbon dioxide in a truck carrying produce specifically low O2 high CO2 you can prevent ethylene synthesis and thus slow the ripening process.
This is helpful when fruits and vegetables are grown in one region of the world and then shipped many miles away to be sold. When our bodies need water we feel thirsty. A rain dance is pretty much out of the question.
Plants produce a chemical messenger, called abscisic acid, to alert the rest of the plant that it is water stressed. Abscisic acid is made in droughted leaves, droughted roots, and developing seeds and it can travel both up and down in a plant stem in the xylem or phloem sounding the alarm. Think back to transport in plants, how does water typically move through a plant? Each stoma singular has two kidney bean shaped bodyguards on either side of the pore, whose job it is to open and close the stoma.
When the guard cells are full of water, or turgid, the stoma is open. When water leaves the guard cells, they become flaccid, and the stoma is closed.
What can you do to prevent yourself from losing any more precious H2O? Close the stomata! How do plants do it? Abscisic acid travels to the guard cells, sending a message that water is scarce. The guard cells spring to attention, and a rush of charged particles exit the guard cells, which subsequently triggers water inside the guard cell to leave, too. The guard cells shrivel and the stomata close! No more water is able to exit the plant through the stomata. Remember that hormones are potent little chemical messengers, but they would lose their effectiveness if they hung around and built up in the tissues of the plant.
So they are broken down and replaced over time. There is so much more to learn about plant hormones! A great textbook for those who want all the wonderful nitty-gritty details is Plant Physiology by Taiz and Zeiger. Spring is in the air and everyone and everything is getting ready for it. Trees that dropped their leaves are breaking out in bloom with new shoots and flowers. Rob is an ecologist from the University of Hawaii. He is the co-creator and director of Untamed Science. His goal is to create videos and content that are entertaining, accurate, and educational.
When he's not making science content, he races whitewater kayaks and works on Stone Age Man. ETYLENE Have you ever noticed that if you put a really ripe, brown banana right next to a bunch of green bananas, the unripe bananas will ripen and turn yellow much faster? Plant Hormones Effect Spring! Choose one of the following categories to see related pages: Plants. Share this Page. You can follow Rob Nelson Facebook. Science Newsletter:. Full List of our Videos. Teaching Biology? How to Make Science Films.
Read our Wildlife Guide. On the Trail of the Egret. Tips for Shooting Smoke Grenade Photos. Pacific Sleeper Shark: Giant of the Deep. Sometimes ornamental shrubs along a foundation overgrow their planting space and are rejuvenated by heading to within 12 inches of ground level.
Many broadleaf shrubs such as burford holly, ligustrum, abelia and crape myrtle tolerate this type of pruning. Other types of heading are topping, dehorning, hedging and clipping. Thinning , on the other hand, removes an entire shoot or limb to its point of origin from the main branch or lateral Fig.
Some shoot tips are left undistributed, so apical dominance is maintained. As a result, new growth occurs at the undisturbed shoot tips while lateral bud development and regrowth is suppressed. Thinning is generally the least invigorating type of pruning cut and provides a more natural growth form of plants. Important in maintenance pruning, thinning cuts are used to shorten limbs, to improve light penetration into plants and to direct the growth of shoots or limbs.
Drop-crotching , a form of thinning used to reduce the size of large trees, involves the removal of a main branch or leader by cutting it back to a large, lateral branch Fig. The cut through the main branch is made parallel to the angle of the remaining lateral. When removing large tree limbs, a series of three cuts are recommended in order to avoid tearing the bark along the main truck and severely wounding the tree Fig. One undesirable form of thinning is the bench cut , where a vigorous upright limb is thinned to horizontal limb Fig.
Vigorous, upright shoot growth, called water sprouts, often result from the "bench" area because of the absence of apical dominance in the horizontal limb.
Such regrowth is weak and often results in an undesirable umbrella-shaped plant. Shoots or limbs having narrow-angled crotches are weaker than those having wide crotch angles Fig. The bark of the adjoining branches becomes tightly compressed or "included," preventing normal wood development.
Winter ice, trapped down in crotches, often causes narrow-angled branches to split. Healing naturally follows pruning or wounding. It starts in the cambium, a thin layer of cells between the wood and bark. Two areas of the cambium, the bark ridge at the junction of two limbs, and the branch collar , a ring of slightly raised tissue where the lateral branch joins the main limb, function to close off the wound between the plant and the pruning cut.
For fastest healing, prune close to the main branch without injuring the bark ridge or branch collar areas Fig. Leaving a stub will slow healing and invite decay. Wound dressings or pruning paint are cosmetic and do little to promote healing of the pruned area. Time of pruning varies with plant species. Prune at times that best complement the growth characteristics, flowering, and other objectives you desire.
Many woody ornamentals are pruned according to their date of flowering. For example, spring-flowering plants, such as dogwood or forsythia, normally are pruned after they bloom.
Pruning spring-flowering shrubs during the dormant season will remove flower buds formed the previous fall. Summer-flowering plants generally are pruned during the dormant winter season.
If plants are not grown for their flowers, the best time for pruning is during the dormant winter season before new growth begins in the spring. Avoid heavy pruning during the late summer and fall because regrowth may occur and make the plants more susceptible to cold injury. This is, indeed, a remarkable result. Even for early and profuse flowering genotypes see results from GM , the production of this number of seeds would be difficult.
Pruning plants of SM in the first flowering, without BA spraying, offered the second-best result, with more than 30 seeds per plant. All the other treatments resulted in significantly lower averages.
The unquestionable conclusion is that the combination of EP, pruning in the first branching event with the additional spraying of BA maximizes the early production of seed of this very late flowering cassava genotype. The top of Figure 6 presents results from CM , which are also relatively easy to describe. This genotype, as was the case for SM , responded well to EP. There was basically no production of seed under DN except for plants pruned in the first branching event without BA spraying.
The statistical significance of these differences is detailed in Figure 6. Results from GM contrast from those of the previous genotypes. This is the only clone among the germplasm evaluated that flowered often under DN Figure 6. Pruning plants under DN was not beneficial. Under EP, pruning in the second branching event with BA spraying resulted in significantly higher averages compared with all the other treatments from GM Since the first branching event in this clone takes place relatively early, there would be only a few leaves below it.
This reduced number of leaves would not be enough to sustain abundant fruit set in plants pruned in the first flowering event. The averages presented in Figure 6 come from the 10 plants representing each clone x treatment combination. These 10 plants were all planted together in a single row.
It is acknowledged that there was no replication for the clone x treatment combinations. Another observed phenomenon arising as a result of pruning was that flowers in the same inflorescence tended to reach anthesis within a few days from each other and with a common disruption of the normal sequence from bottom to top. This phenomenon is clear in Figure 7 but is also obvious from Figure 5.
Figure 7 Effect of pruning and application of the plant growth regulator BA. The photograph on the left illustrates inflorescence at the first branching event from SM after pruning and BA application. The flower within the square is hermaphrodite, whereas flowers within circles are female only. The three photographs on the right show a typical male flower top , a female flower with intermediate middle , or full development bottom of anthers.
Finally, the germination capacity of botanical seed produced after pruning was evaluated in three separated batches following the standard procedures at CIAT. It was occasionally observed, within the plant rows, that one or two plants had a very different flowering pattern.
For example, nine plants would flower and branch three times during the length of the trial but the remaining plant in the plot would not do so, not even once. Similarly, in a given plot all plants except one, would fail to flower.
Moreover, this flowering plant may have up to two levels of branching e. These outlaying plants, however, did not prevent identifying clear responses from the different genotypes to the light treatments, but explain some apparent inconsistencies in the data presented. They were included, however, in the respective plot data.
The nested approach to analyze data in Table 2 allows for a series of dichotomous decisions illustrated in Figure 3. The first contrast DN vs EP clearly indicates that extended photoperiod has a positive effect and results in a significantly higher number of fruits and seeds. The contrast between the performance under DN vs EP in each of the four genotypes agreed with earlier reports Pineda et al.
EP is a pre-requisite for pruning clones that do not flower under normal conditions. A second decision that the researcher must make relates to the convenience of pruning, provided that EP is available and that genotypes respond to it, or else that genotypes would eventually flower under ordinary conditions. Pruning can be done whenever plants from this genotype flower under DN, but EP would allow pruning much earlier.
The earliest experience pruning young branches was on cassava germplasm adapted to the Guangxi province in China. These plants were grown under DN, in a lowland environment but at a higher latitude which offer a wider variation in the duration of photoperiod through the year than at CIAT station.
There was a positive response to pruning as data from Table 2 indicates, corroborating the unpublished experiences in China.
A key effect of pruning is to prevent abortion of inflorescences, particularly those produced in the first branching event.
A similar result was reported by Hyde et al. This anti-ethylene plant growth regulator failed to hasten flower initiation in cassava, but sustained floral development and prevented their abortion particularly in the first branching event.
Having accepted that pruning is advantageous, then we have to choose between pruning at the first or second flowering event. Results suggest that it is generally better to prune at the first branching event. The final element in an ideal protocol for the production of cassava seed relates to the convenience of spraying BA.
Results would recommend the use of this plant growth regulator both in plants pruned in the first or second branching event. These are recommendations that can be made based on the results presented in Table 2. The analysis of the response from different genotypes was not the main purpose of this study which focused in the effect of pruning and application of BA treatments across genotypes Table 2.
Figure 6 was included mainly to highlight that genetic differences seem to matter. Responses of the three genotypes, without pruning under DN and EP agree with parallel studies focusing on the effect of EP alone Pineda et al. For SM pruning in the first branching level was clearly the best option. In the case of GM , on the other hand, pruning in the second flowering event makes sense.
Finally, CM would accept pruning at either branching event. Unfortunately, there was not replication for the genotype x pruning combinations in this study. Therefore, future studies should confirm that for genotypes that flower relatively early, pruning in the second branching event without BA application may result in higher seed production than other treatment combinations.
Perera et al. These authors also reported the occurrence of hermaphrodite flowers, although at a very low frequency 0.
There was considerable variation in these figures depending on the genotype. An interesting effect of pruning plants was the generalized feminization of flowers. As a result, there was a sharp increase in the number of hermaphrodite flowers e. Moreover, in many cases, what should be male became a female-only cyathia. The feminization of flowers is a positive development and explains the unprecedented number of seeds per plant that could be obtained, for example, in SM The occurrence of hermaphrodite flowers would facilitate self-pollinations and thus a wider utilization of inbreeding for the genetic enhancement of cassava.
The advantages from the use of partially inbred progenitors in cassava breeding has been listed Ceballos et al. However, hermaphrodite flowers present a new problem. Emasculation of anthers would be required to guarantee the production of hybrid seeds in directed crosses.
This is an unprecedented procedure in cassava. There are ongoing efforts to foster the feminization process e. Capacity for successful pruning can be quickly acquired after a short training. It was observed that proper pruning at the first branching event is easier than at the second one, because the chronology of events in the first flowering event is slower than in the second. It was easier, therefore, to detect on time the globular shaped shoots that were ready for pruning in the first flowering event.
On the other hand, branches in the second flowering event seem to develop much faster and as a result, some of the pruning was done later than desirable e. The botanical seed produced behaved normally when germinated. This is obviously a key requirement for the protocols suggested in this study to be useful.
The most important finding of this work is that pruning young branches prevents the abortion of the first inflorescence, fostering seed production much earlier than in untreated plants of late flowering genotypes. EP is fundamental for the induction of the first branching event.
Therefore, a combination of EP with pruning is a sensible recommendation. Since breeders are interested in the early production of seed, it seems also reasonable to focus on pruning at the first flowering event.
The combination of extended photoperiod, pruning, and BA application was particularly advantageous for late flowering genotypes such as CM and SM , which otherwise produce very little or no seed at all.
Early flowering genotypes such as GM seemed to react differently to these treatments. However, breeders seldom need to foster flowering and seed production in early flowering cassava. Future research should validate these preliminary results regarding the reaction of different genotypes. The reaction to pruning may be different in other locations.
The advantages of pruning young branches were first detected near Nanning city in China lower than m. Pruning has been successfully used at Kasetsart University in Thailand. This would suggest that the advantages of pruning reported in this study are not restricted to Palmira, Colombia, nor to the germplasm used in the present study. The datasets generated for this study are available on request to the corresponding author.
MP conducted the experiment, took data, performed the pruning, and participated in the analysis of data. BY and YT were involved in the first evaluation of the effect of pruning branches. NM and SS were in charge of the field management and electric system installation. HC coordinated the work in Colombia, analyzed data, and wrote the manuscript.
TLS participated in writing and editing the manuscript. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
0コメント