Sabtu, 12 Januari 2008
A good fruit tree should not make a good shade tree. However, when pruning is neglected, many apples and pears become better shade producers than fruit producers. Standard-sized trees often outgrow the reach of ladders or pruning hooks. Backyard and commercial growers have come to prefer dwarf or semi-dwarf trees which are not as tall and are easier to prune, spray, and harvest without the use of ladders.
A neglected but otherwise healthy tree will usually show a marked improvement in fruit quality as a result of pruning. Fruit buds begin developing in the growing season previous to the one in which they mature into fruit, and more are initiated than can be fully developed into fruit. Growing conditions during the season of bud initiation and the subsequent winter will affect the number of buds which flower, and certain cultivars are "alternate bearers" that seldom initiate many buds during a year with a heavy fruit crop. In any case, by late winter the buds for the coming summer's crop will be very evident. Buds only appear on two or three year-old twigs or spurs which are no thicker than a pencil.
The primary purpose of pruning is to increase sunlight penetration, remove less productive wood, and shape the crown into an efficient, stable form. If left unpruned, the quantity of fruit produced might be greater, but the quality much lower. Pruning increases fruit size, promotes uniform ripening, increases sugar content, and decreases disease and insect problems by allowing better spray coverage and faster drying following rainfall. It also allows easier access for timely harvesting.
White Apple Leafhopper.
The white apple leafhopper (Typhlocyba pomaria McAtee; Homoptera: Cicadellidae) is a native insect that is widely distributed throughout the apple growing regions of the United States and Canada. Several leafhopper species are found in abandoned apple orchards, but the white apple leafhopper is the species that predominates in commercial plantings. While apple is probably the only host on which this leafhopper overwinters, it may also infest peach, plum, cherry, and hawthorn during the growing season.
The white apple leafhopper is a leaf feeder and does not directly attack the fruit. Leafhopper nymphs and adults insert their piercing/sucking mouthparts into plant cells and remove the contents. As sap is sucked from the leaves, green tissue is destroyed causing foliage to become speckled or mottled with white spots. Heavy feeding may cause the entire tree to appear white or silver. Damaged foliage interferes with photosynthesis and reduces plant vigor resulting in smaller fruit size, poor fruit color, decreased bud formation, and fruit drop.
In addition to direct leaf injury, these leafhoppers excrete resin-like material, in deposits called tarspots. Tarspots on the fruit substantially reduce quality and value. Most of the significant fruit spotting is associated with the second generation of white apple leafhopper.
Damage by white apple leafhopper is usually more prevalent in well-maintained orchards with succulent leaves. It is more common on Rhode Island Greening, McIntosh, and Red Delicious than on other apple varieties. White apple leafhopper outbreaks are favored by moderate drought conditions.
Description and Life Cycle
White apple leafhopper adults are creamy white to yellowish-green in color and about 3 to 4 mm (1/8 inch) long. They hold their wings in a roof-like position when resting and appear as tiny wedges when seen from above. Adults are active and fly readily when disturbed.
The white apple leafhopper overwinters in the egg stage under the thin bark of twigs that are approximately 1.25 cm (1/2 inch) in diameter. The eggs are less than 1 mm (1/25 inch) long, cylindrical with tapering ends, and creamy white in color. The egg-laying sites appear as elongate, oval, blister-like swellings about 1.5 mm (1/16 inch) in length, which characteristically run perpendicular to the terminal growth. Overwintering eggs are found on one- to five-year-old wood, but are most often present on two-year-old wood.
Overwintering eggs begin to hatch just before apple blossoms open and usually complete hatching by petal fall. The emerging nymphs move to the undersides of older leaves and feed almost exclusively on the same leaf throughout development. The nymphs, which are wingless, move little as they feed, but will run actively when disturbed.
White apple leafhopper has five nymphal stages. First and second stage nymphs are about 1.0 to 1.5 mm (1/16 inch) long, pale white, with dull red eyes. The third stage nymphs have dull white eyes and developing wing pads. The fourth and fifth stage nymphs are similar in appearance to third stage nymphs, but reach a length of 2.8 mm (1/8 inch). Later stages also become more yellowish or yellow-green in color. The nymphal stages are separated by molting periods when the exoskeleton is shed. These transparent cast "skins" frequently remain hanging from the underside of the leaf. Nymphs of the first generation are most abundant in May and early-June. They are found on cluster leaves close to the trunk or large limbs; they are not found on actively growing terminal shoots.
First generation adults begin to appear in early-June, with males emerging a few days before females. They mate early in the morning and lay eggs about two weeks later. Eggs that will hatch into second generation nymphs are laid in petioles, mid-ribs and large secondary veins on the undersides of leaves. Females lay eggs for about three weeks, each depositing up to 60 eggs. First generation adults gradually die off after five or six weeks and are not observed during mid- to late-July.
Second generation nymphs appear in early-August with adults appearing from mid- to late-August. Adults remain active throughout September but diminish rapidly in number by October. The overwintering eggs are laid under apple tree bark from mid-August to mid-October.
Contrast with Potato Leafhopper
The damage caused by white apple leafhopper feeding is different than that caused by the potato leafhopper, Empoasca fabae (Harris) on apple; feeding by potato leafhopper causes the tips of leaves to turn yellow and brown and to curl up. The bronzed, dried appearance of leaf tips is referred to as "hopper burn," and heavy infestations can result in stunted plant growth. While white apple leafhopper is found on cluster leaves and not on actively growing terminal shoots, potato leafhopper is more of a threat to young, non-bearing fruit trees and young, tender foliage.
Potato leafhopper is light green. White apple leafhopper can be distinguished from potato leafhopper by the tendency of white apple leafhopper to walk forward and backwards while potato leafhopper walks sideways as well as forwards and backwards. Potato leafhopper has a wide host range, including potatoes, beans, and alfalfa. Potato leafhopper develops throughout the year in the southern United States near the Gulf of Mexico, and migrates northward each growing season rather than overwintering in northern states. The appearance of potato leafhopper is therefore less predictable because its migration is dependent upon the jet stream and weather patterns. White apple leafhopper overwinters in northern areas.
Monitoring and Action Threshold
The need for control of white apple leafhopper should be determined at petal-fall, when wingless nymphs of the first generation can be found. The presence of white stippling on the upper surface of leaves indicates that nymphs are feeding beneath. Leafhoppers should be sampled from the underside of leaves, especially on suckers or older terminal growth. When monitoring the second generation, keep in mind that watersprouts often have heavier populations of leafhoppers than other areas of the tree. Count the number of leafhoppers on ten leaves from each of ten trees, and calculate the average number of leafhoppers per leaf. Treatment is suggested if there is an average of more than 0.5 leafhopper nymphs per leaf.
Natural enemies include parasitic wasps that attack leafhopper eggs; predators such as spiders, lacewings, and minute pirate bugs; and a fungus. In commercial orchards, natural enemies usually do not adequately control the white apple leafhopper.
The insecticides most effective in the control of leafhoppers are methomyl (Lannate*) and formetanate (Carzol*). Dimethoate (Cygon) and endosulfan (Thiodan*) are also effective. Carbaryl (Sevin) and oxamyl (Vydate*) are very effective but will cause fruit thinning if used within 30 days of bloom; if they are used, it is best during very early petal-fall rather than late petal-fall for minimal thinning. Be careful with emulsifiable concentrate (EC) formulations used near petal-fall as they tend to increase the potential for fruit russetting. Note that insecticides commonly used at petal-fall for control of plum curculio and codling moth, such as phosmet (Imidan) and azinphos-methyl* (Guthion) are not effective in controlling leafhoppers. Good control of the first generation should help suppress second generation leafhoppers so that additional control is not needed.
Young leafhoppers are easier to control than adults. The first brood is a better target than the second brood because the hatch is relatively synchronous, making a greater proportion of the more susceptible nymphs present at one time. Thorough spray coverage of upper and lower leaf surfaces is necessary and considered essential for effective control with contact insecticides.
* indicates a restricted-use material.
NOTE:Disclaimer - This publication contains pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author, The Ohio State University and the Ohio State University Extension assume no liability resulting from the use of these recommendations.
There are 12 or so species of Fragaria and the genus is native to the north temperate regions (Eurasia, North America), and also extends into North Africa and down through tropical American mountains into temperate South America (e.g. Chile). The number of sets of chromosomes varies from species to species ranging from 2 sets in the Wild Strawberry Fragaria vesca to 8 sets in the Modern Garden Strawberry Fragaria ananassa.
In a strict botanical sense, the strawberry fruit is not a true fruit, but is termed a pseudocarp. Fragaria belongs to the family Rosaceae in which there are a whole lot of individual female reproductive organs, termed carpels, in the flower. Each carpel consists of a stigma, style and ovary and all the carpels are inserted on to a fleshy receptacle. In Fragaria, the receptacle swells into the red-coloured 'fruit' we know as a strawberry and over its surface are black dots, each dot being an individual true fruit (a true fruit being the ripened ovary). The individual true fruit are termed achenes these being small, dry single seeded fruit that do not split open. It is interesting to contrast the strawberry with the Blackberry (or any other species in the genus Rubus) which is also in the Rosaceae and which also has multiple carpels inserted on a receptacle. Instead of the receptacle swelling to form the fruit, the individual ovaries of the carpels become black and fleshy and in combination they form the Blackberry. So strictly speaking, the Blackberry is also not a true fruit but an aggregation of separate fruit, but in a loose botanical sense, it is OK to call strawberries and blackberries fruit.
Strawberries are eaten by birds which disperse the seeds widely. Strawberry plants also spread vegetatively using runners and this enables them to be easily transplanted and propagated as clones. Strawberry species are generally dioecious (male and female flowers on separate plants) but hermaphroditic flowers did occur rarely in the wild and these were selected for in domestication because it simplified crop production and enabled a crop to all be cloned from a single source.
The Wild Strawberry or Wood Strawberry Fragaria vesca is native to the temperate regions of Eurasia and North America. It has become distributed worldwide and is sometimes found naturalised in southern Africa. It is a diploid species (i.e. 2 sets of chromosomes).The finding of strawberry achenes in neolithic archaeological excavations, shows that wild strawberries have been eaten by people since the earliest of times. Fragaria vesca was being cultivated in Europeans gardens by the 1500's (Renaissance) and after about 1530, cultivated strawberries are clearly larger than wild ones, indicating selective breeding. Although Fragaria vesca is still grown in gardens for domestic use, it is not used in commercial strawberry production because of the development of the Modern Garden Strawberry Fragaria ananassa.
The Hautbois or Musk Strawberry Fragaria moschata is native to highland areas from France through to Siberia. It is a hexaploid species (i.e. 6 sets of chromosomes). Like Fragaria vesca, it started being cultivated in European gardens from the 1500's and was still being cultivated widely in the 1600's. However, with the arrival of Fragaria virginiana and Fragaria chiloensis from the New World, growing of this species became severely curtailed in favour of these new, more favourable species and especially the new Modern Garden Strawberry that arose through hybridization of these two species.
The Virginia Strawberry Fragaria virginiana is native to North America and its flavour, size and abundance made it a popular fruit amongst Indian tribes and also amongst European colonists. During the 1620's, it started being cultivated in Europe. It is an octoploid (8 sets of chromosomes).
The Chilean Strawberry Fragaria chiloensis is also an octoploid and native from Alaska to California. It also evidently became dispersed in prehistoric times by birds to Hawaii, Chile and Argentina. It had been domesticated by the Araucanians in Chile before the Spaniards arrived. They selected for large-fruited varieties. The colonists spread it widely within Central and South America but it was evidently only introduced to Europe in the early 1700's.
The Modern Garden Strawberry Fragaria ananassa is also an octoploid. It is a hybrid between the domesticated Fragaria virginiana with its hermaphrodite flowers and tasty fruit, and Fragaria chiloensis with its large fruit. The hybrid arose within Europe and might have done so a number of times, whenever the two parent species were interplanted. It is of such superior size and quality that it has become the main species in commercial strawberry production. Strawberry varieties have been selected to favour particular climates and to be day-length neutral so that they flower and fruit under both short and long day lengths, thus enabling them to be harvested over a long season in frost-free regions.
Strawberry fruit are eaten raw or used in making juice, desserts, jam, syrup and wine. Leaves are used in blended herbal teas. Leaves and roots are believed to have medicinal benefits in terms of easing diarrhoea, digestive upsets and gout. The fruit juice is evidently used externally to counteract sunburn, skin blemishes and discoloured teeth.
One of the most beautiful and most tasty fruits in the entire world would be the strawberry. This red sweet berry is loved and eaten throughout the entire planet. As like most fruits, strawberries taste much better when they are homegrown than they do store-bought. The reason being that many of the fruits and vegetables that are sold in stores are more than likely to be genetically engineered and dusted with pesticides. Organically grown fruits have a much better quality and taste than those that are grown artificially.
Starting a strawberry garden can be a great idea if you are planning on sprucing up your garden this spring. You will have the opportunity to go out and pick fresh ripe strawberries from your own yard to add to your morning cereal or just for a tasty snack.
Strawberries are very easy to grow and unlike most plants, strawberries can yield crop just months after planting.
Let’s get started!!! The first step to starting your strawberry plant is to pick up bare-root strawberries as soon as they are available. You can usually purchases these in most areas as late as April and in a 4-inch container.
Strawberries can live almost anywhere. There are actually three ways which you can plant your strawberries. These three include are in the ground, a hanging plant, or a strawberry pot.
You can purchase your strawberry plants from most nurseries. You can also mail order or purchase them over the Internet. You want to make sure that the mail order is very reliable and reputable. You want to avoid planting strawberries from old plants because these types of plants are more than likely disease infested. If you can’t plant your strawberries right away after they arrive, than you should place them in a plastic bag and place a moist material, like wood shaving or peat moss, around the roots of the plant. You should then store them in the refrigerator. You can safely store them there for up to two weeks. Here is a list of websites where you can order strawberry plants and plugs:
Care and Harvest of Strawberries
by National Gardening Association Editors
You won't be idle until your first harvest. You must not let the new plants set berries in their first year. They will try to fruit, but you must pick off the blossoms as they appear. This way, instead of fruiting, the mother plants will produce vigorous daughters that will yield well the following year.
Keep Weeds Away
Keep the bed weed-free throughout the growing season. Some people use a sheet of black plastic to smother weeds, leaving holes for the strawberry plants, but that's more work than weeding when it comes time to position the runners and the daughter plants.
Training the Runners
After 5 or 6 weeks in the ground, your plants will begin to "run." A first daughter plant will form and root, then the runners will set more daughters. Keep only the first daughter of each runner. It will bear better than a second or third daughter on the same runner. When most mothers have produced daughters that are ready to take root, it's time for you to establish the 9-by-9-inch spaced row system. Although it's more work, it's more berries. Let five strong daughters from each mother plant take root; clip off all others. (If you don't have five daughters on a plant, make do with what you have.) As these daughters grow, space them around the mother at 9-inch intervals. Weigh the runners down with soil, stones, or hairpins to hold the daughters in place; they'll root by themselves.
It will take two or three passes over the course of the summer to arrange the plants correctly and get rid of unwanted runners. While the arrangement may not look quite as tidy in your strawberry patch as it does on paper, you will have created three parallel rows with plants spaced roughly 9 inches apart in each one. Unlike other systems in which all plants are permitted to run freely, this system discourages sibling rivalry and gives each selected plant plenty of room to grow. The result is more and bigger berries. When the first bearing season is over, you'll do best to till in all the plants and start again. Each successive year you prolong their lives will yield fewer berries - and more weeds and disease.
Two Berry Beds
To have strawberries every year, you should maintain two beds: one to bear fruit and one to produce next year's fruit-bearers. After the harvest, plant a short-season vegetable where the berries were, if you like, then a winter cover crop like buckwheat or rye. Crop rotation has many advantages: the roots of the strawberry plants don't have a chance to get bound up, infestations of diseases are less likely, and rotation is an effective method of weed control. The following spring, you'll set new strawberry plants in that bed and begin the cycle again. Many gardeners prefer to renovate their beds, thinning out most of the plants and leaving some strong ones to produce runners and daughter plants for the third year. If you've enjoyed a productive, disease-free season, you may decide to renovate at least part of the bed for another year or two before cleaning out the whole bed entirely:
Renovating the Bed
Here are the basics in renovating an existing strawberry bed.
1. Just after harvest, cut off all the leaves with a scythe, sickle, or lawnmower set high enough not to hit the crowns.
2. Turn under the two daughter plants on either side of each mother row (preferably with a tiller), which should leave a 6-inch- wide row.
3. Add a complete fertilizer such as 5-10-10 (1/2 pound per 25-foot row) to the bed and get rid of all weeds. Thin the plants to stand 9 inches apart, leaving only the strongest ones.
4. Allow only two runners from each plant; set each runner 9 inches from the mother plant on either side.
5. Side-dress with 2 1/2 pounds of 5-10-10 or its equivalent per 100 feet of row.
6. Apply winter mulch as before. Await spring and your second - and somewhat smaller - harvest.
Harvesting Your Berries
In the second year, the berries will ripen about 1 month after the plants bloom, with the bigger berries developing at the center of each cluster. To harvest, don't squeeze a ripe berry; pinch the stem behind it with your thumbnail. Every 2 or 3 days, pick all the ripe berries. Avoid picking green-tipped berries - they're not fully ripe. They'll taste much better in a day or two. Don't leave berry remnants on the plants because they encourage plant rot. You can expect 2 to 3 weeks of harvesting for each variety. If you find yourself deluged by berries, you can make them into jam or freeze them.
by National Gardening Association Editors
Strawberries will do best in soil that has been thoroughly prepared. If your future strawberry bed was plowed last year, you're ahead of the game. But if you're starting with land that was in sod, allow an extra year or the soil will be tough to cultivate, and you'll really pay later when you are confronted with weeds (especially grass) and grubs. Strawberries do best in soil with a pH of 5.5 to 6.5. Apply aged manure and a complete fertilizer such as 5-10-10 (1/2 pound per 25-foot row) before planting in the spring. To further improve the soil, you can plant a winter cover crop. If you have heavy soil, raised beds will provide better drainage and encourage healthy roots.
Planting the Berries
You can usually set out your new plants in the strawberry bed when the trees in your area are just beginning to leaf out. Suppliers try to ship them at the appropriate time for your region. If
you're not ready when the plants arrive, you can store them in the refrigerator for a couple of weeks. Let out any moisture from the shipping bag and wrap the roots in plastic. Do not let the roots dry out. Space your rows 4 feet apart, and leave 18 inches between plants. Cut back the roots of your new plants to not more than 6 inches long; put them in a bucket and soak the roots in water for about an hour just before planting. Make absolutely sure you set them in the ground at the right depth so the roots don't dry out and the crown isn't buried. Pack the soil against the roots, and water each plant with about 1/2 pint of water mixed with a soluble fertilizer; don't overdose.
Getting Ready for Strawberries
by National Gardening Association Editors
Probably nothing beats the taste of a just-picked, sun-ripened strawberry. Strawberries are loaded with natural sugars, but these sugars rapidly convert to starch once the berry is picked. So it is not mere pride that makes a freshly picked home-grown strawberry taste better - it really does. The fresher the berry, the sweeter the taste. Strawberries are high yielders. From a single, well-cared-for 2-year-old plant, you can expect to harvest 1 to 2 quarts of strawberries. That's 50 to 100 quarts of berries from a bed 15 feet long and three plants deep - about 50 plants.
Keep Planting Strawberries
You can maximize yields by continually renewing your strawberry bed with new plants. Many gardeners try to keep old plants producing year after year, but this inevitably leads to decreased yields and increased disease problems. You can start out in the spring with ten plants that will each produce five healthy daughter plants in the first year - and they'll bear an abundant crop of strawberries the second year. Keep two beds in rotation and every year you can count on 50 to 100 quarts of juicy red berries - enough for about thirty strawberry-drenched shortcakes and fifty pints of preserves to enjoy all winter and fifty helpings of Sunday brunch strawberry waffles, not to mention the sweetest possible berries for eating straight out of the garden.