Category: seminar

Asexual or vegetative reproduction is possible with all plants if there is the presence of meristematic tissue, it occurs naturally by means of:

• Runners (strawberry plants)
• Tubers (potato)
• Rhizomes(horsetail)
• Bulbs (tulips)
• Corms (gladiolus)

 

Humans can manipulate vegetative propagation through means of cuttings,

• Hardwood cuttings (roses, deciduous trees)
• Softwood cuttings (lavender)
• Grafting (fruit trees)
• Dividing (perennials such as daisy)
• Root cuttings (Japanese anemones)
• Leaf cuttings (Christmas cactus, snowdrops)

 

The advantages of asexual reproduction are only one parent plant is needed to reproduce offspring, which is genetically identical or a clone. This ensures that desirable traits and good features are continually passed on through generations without mutations or variations in the plants, this feature is especially important in plants prized for their showy flowers, such as roses and dahlias. Asexual reproduction is usually much faster than propagating by seed, a good example would be the buttercup plant, which quickly colonizes by means of runners. Asexual reproduction also requires less energy to reproduce, it does not expend energy in creating flowers to attract pollinators, nor is it dependent on wind or insect pollination.

 

The disadvantages to asexual reproduction is lack of genetic diversity, the offspring are clones of the parent plant with no diversity which makes them unable to quickly adapt to the stress of disease and pest pressure. Rapid changes in the climate or growing conditions could be the cause of extinction.

 

Sexual reproduction in flowering plants produces offspring that are genetically different from the parent plant, this creates diversity, which can improve the chance of survival. Plant diversity and mutations will create offspring that are better able to respond to disease and pest pressures, as well as changes in growing conditions. Fertilized seeds can be dispersed great distances by means of wind and bird transfer, this enables the plant to spread and not compete with itself for light and nutrients. Unique variations or new breeds are created through genetic diversity in plants.

Raspberry plants flourish in our northwest climate, but it is important to start the crop off correctly by choosing a site with well drained soil and full sun, they can be grown in raised rows if standing water is a concern in the winter. They should be planted 2 1/2 feet apart in rows spaced 8 to 10 feet, raspberry flowers are self-fertile, pollen is transferred by visiting insects seeking nectar. I would choose to trellis using a standard cross system at 4 1/2 feet in height. The ideal PH range is 6.0 to 6.5, if the PH is less than 5.5 lime should be applied to ameliorate the soil.

There are two main cultivars of raspberries, summer-bearing (June-Bearing) and Fall-Bearing (Everbearing). The roots and crown are perennial with a lifespan of thirty to forty years, the canes are biennial, primocane is the first year growth and floricane is the second year growth. It is a good idea to keep the two cultivars in separate beds, this will insure that the correct pruning cuts are performed at the right times throughout the year.

June Bearing

Summer bearing raspberries initiate flower buds on first year canes (primocanes) from August through September, the canes overwinter, bloom, and produce fruit the following spring and early summer. While the fruiting canes (floricanes) are bearing fruit, new green primocanes begin to emerge, commencing the cycle for next years’ crop of berries. After harvest the old fruiting canes should be removed to allow for light and air circulation on the new primocanes, this will promote healthier growth and maximize yields the following year. Topping primocanes in the fall leave the susceptible to frost damage, instead wait until February and trim the tops 6 inches from the top of the 4 1/2 foot trellis wire, this forces lateral branches, improving the size and quality of the fruit. I would extend the growing season by choosing a variety of June bearing cultivars based on their harvest season as follows:

Willamette: short early harvest season

Meeker: Long mid-season

Algonquin: Mid-late season

Sumner and Chilliwack: Late season

My raspberry bed at home, before pruning

 

 

 

After Pruning

 

In an ideal situation an apple tree would be trained and pruned the first year it is planted. Training helps develop good form and structure while the tree is young and the desired crotch angle of 45-65 degrees can be obtained by gently manipulating the branches by tying them to sandbags, using limb spreaders fashioned from toothpicks or wooden spreaders in lengths of six to eighteen inches. The development of watersprouts can be avoided by training branches to bend at a 45 to 65 degree angle which inhibits the flow of auxin.   Annual training and pruning ensures a strong framework with the proper shape and form and structure that will help the tree live longer and make a higher quality of fruit, and make for less pruning as the tree matures.  It is important to distinguish the difference between primary growth and secondary growth. Primary growth is an increase in the length of the shoots and is responsible for the trees height and width. Pruning primary growth enables you to control the height and width of the canopy. Secondary growth is the increase in thickness of the stems, stouter and stronger branches can support the weight of the tree’s fruit.

The first step is to have a clear plan, step back and notice the sun’s path and direction in relation to the tree. Recognize your reasons for pruning, aim to maximize fruit yield, open air space, and allow for light penetration.  Before making your first cut it is vital to disinfect your pruners and shears with rubbing alcohol. The first decisions are clear, remove all dead or diseased wood and crossing branches. Next all suckers emerging from the base of the tree should be removed, as they are from the root stock and sap energy from fruit yield.  Depending on the season, age, and health of the tree, removal of a large percentage of watersprouts should be considered since they take energy from the tree and only produce fruit when pulled or forced to bend. Watersprouts pruned in the winter make excellent scion wood for future grafting endeavors.

Before moving on to heading cuts and thinning cuts it’s best to keep in mind that only ten to thirty percent of tree should be removed while pruning. Thinning cuts remove the entire branch or twig, reasons for thinning are to maintain an open shape to allow maximum sun exposure and to control the growth of overly tall leaders, crossing branches, and limbs with narrow crotch angles. Heading cuts remove part of the tree’s branch to the terminal bud, stopping or slowing the flow of auxin while promoting growth and bud development. While pruning aim for an open bowl shape for optimal light penetration and air flow.

   I encountered this worm while pruning the liberty apple trees this week.