- Author: Ed Perry
If you do not prune your trees enough, they will become too tall to harvest, even with a tall ladder. If you have an unpruned fruit tree in your garden, you know that most of the fruit grows in the top. Yearly pruning is necessary to keep the tree at a reasonable height, for instance, no more than 10 or 12 feet high. If your tree is already overgrown, you may want to reduce its height gradually, say over a two-year period.
The main objectives of pruning mature fruit trees are to reduce the number and increase the size of the potential crop, to develop new fruit wood, to remove interfering and broken branches, and to contain tree height and spread for convenient harvest. Most fruit trees, when not pruned, produce more fruit than they can size and mature properly. You can prevent such overproduction with yearly pruning.
Persimmons, many figs, quinces and pomegranates bear fruit on current season's growth. When you prune these trees, remove old and weak branches, leaving some younger branches to produce new growth and fruit the coming year. Overcrowding and lack of sunlight will cause branches to die, so you need to thin out some branches to allow light infiltration into the tree so that the fruit wood stays healthy.
Nut trees such as almonds and walnuts do not need as much pruning for height control as fruit trees. You harvest nuts by knocking them down with a long pole, rather than by hand picking, so the trees can be much taller.
Fruit Tree Resources
Fruit Trees: Training and Pruning UC ANR Publication
The California Backyard Orchard For more details about training and pruning deciduous fruit trees.
Citrus and Avocado Trees Require Little Pruning For information on pruning citrus and avocado trees.
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.
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- Author: Ed Perry
Soil solarization is a simple technique that you can use in your home garden to reduce or eliminate many soil-inhabiting pests. Solarization works by heating up the soil in the presence of moisture to temperatures that are high enough to kill many fungi, nematodes, weeds and weed seeds.
In order to solarize your soil, you must leave a clear plastic tarp on the soil surface for 4 to 6 weeks during the hottest part of the year, which of course is now. Black or colored tarps will not allow the soil to get hot enough, so you must use transparent plastic. Polyethylene plastic 1 mil thick is the most efficient and economical, but you must handle it carefully because it rips and punctures easily.
Before laying the plastic down, clean up all weeds, debris and large clods, then level and prepare the soil as for planting. The closer the tarp to the soil, the hotter the soil becomes. Air pockets caused by clods or debris will decrease the effectiveness of the treatment. A smooth, bare soil surface is best.
You must also wet the soil before covering it with the tarp. The moisture causes organisms to be more sensitive to heat and also allows the heat to penetrate deeper into the soil. It's best to wet the soil thoroughly before laying the tarp.
While some pests may be killed within a few days, 4 to 6 weeks of treatment in full sun during the summer is needed to kill most pests with solarization. The highest soil temperatures will occur when the days are long and hot, and when the sky is clear and there is no wind.
Many disease organisms are effectively controlled with solarization, including the fungi that cause Verticillium wilt, Fusarium wilt and damping off of seedlings. Many annual weeds are also controlled, but perennial weeds such as Bermudagrass, field bindweed, johnsongrass, and yellow nutsedge are suppressed but not completely controlled by the procedure. Nematode populations are also reduced, but the heat may not penetrate deep enough to destroy those below the top foot of soil. Nematodes should be controlled well enough for shallow-rooted crops.
Once the solarization is completed and you've removed the tarp, take care not to disturb the soil very much. Turning the soil can bring up living weed seeds and diseases that were too deep to be destroyed by the heat.
Read the publication Soil Solarization for Gardens & Landscapes for more information.
- Author: Anne E Schellman
The University of California Cooperative Extension (UCCE) Master Gardeners of Stanislaus County are teaching a free Managing Pests in Your Vegetable Garden class on Thursday, July 18, 2019 from 6:00-7:30 p.m. at the Agriculture Center on 3800 Cornucopia Way in Modesto at Harvest Hall, Rooms D&E.
Join us for a free class about common pests that plague warm-season vegetable gardens. Learn how to identify insects, diseases, and weeds and how to control them using less-toxic methods.
This family-friendly class is open to everyone. Participants will receive free seeds (while supplies last). Our instructor for the class is Ed Perry, Environmental Horticulture Advisor (emeritus) for Stanislaus County. This class is free, but please visit http://ucanr.edu/vegpests2019 or call Anne Schellman at (209) 525-6862 to sign up. Space is limited, so please reserve your seat today.
If you haven't already, please “like” us on Facebook and Twitter @UCMGStanislaus so you never miss an announcement for a class or workshop.
- Author: Ed Perry
Home gardeners often become concerned when their fruit trees begin dropping fruit prematurely. In some cases, fruit drop is nature's way of reducing a heavy fruit load. In other cases, premature fruit drop may be caused by pests and diseases, adverse weather conditions or poor cultural practices.
Apples may have a couple of periods when fruit drop occurs. The first is often after the flower petals fall off and may last two to three weeks. The very small dropping fruits are the ones that were not pollinated, so will not develop further. Many fruit species need to be pollinated by bees. Lack of pollination may be the result of cold or wet weather during the bloom period, or by a lack of honey bees. Also, if there is freezing weather just before the flower buds open, more fruit drop may occur.
Other adverse weather conditions may also contribute to fruit drop. For example, persimmons may drop if the weather turns suddenly hot in spring, just as the small fruits begin to develop. Trees not receiving adequate irrigation water would be more prone to dropping fruit.
Pests and diseases may contribute to the problem of premature fruit drop. Cool wet weather during the bloom period of walnuts often results in infections of walnut blight, a bacterial disease that damages catkins, leaves, and newly-pollinated nuts. Infected nuts may drop prematurely. Premature ripening and fruit drop often occurs in apples and pears that are infested with codling moth larvae.
In apples and pears, a second drop occurs once the fruits are about the size of marbles, usually in May or June. This is commonly referred to as “June drop.” Fruit drop at this time of year is thought to occur as a result of competition between fruits for available resources.
Some fruit tree species, such as plums, may experience a mid-summer fruit drop. Proper fruit thinning can help to prevent this. How much to thin depends upon the tree species. With peaches and nectarines, it's important to make room on the branches for each fruit to grow to 2 ½ to 3 inches in diameter. Thin by pulling off ¾ to 1-inch long fruit in April and May, leaving one fruit every 6 inches. This results in more fruit on the ground than on the tree, but it's important to produce large, flavorful fruit and to minimize limb breakage.
Thin apricots when the fruit is about ¾ inch in diameter, leaving 1 apricot every 3 inches. Thin plums when the fruit is ¾-inch-long, leaving 1 plum every 4 to 6 inches. Thin apples after the usual May or June drop. Leave 1 apple every 6 inches or allow only 1 apple to remain per spur. Asian pears should be thinned to leave only 1 fruit per spur.
When mature fruit begins to drop, it's a sign that the fruit is ready for harvest.
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County.
- Author: Ed Perry
Aphids are a common garden pest in spring and are attracted to new, succulent plant growth. This year, heavy aphid infestations can already be found on roses and fruit trees.
Aphids often first show up along the edges of the garden. Many species infest the undersides of leaves first, so turn leaves over while looking for aphids. On some plant species, especially plum and apple trees, aphid feeding causes the leaves to curl. Once this happens, it's harder to obtain control because the curled leaves protect the pests from natural enemies or sprays.
When you find aphids, check for evidence of natural enemies like lady beetles, lacewings, syrphid fly larvae, and the mummified skins of parasitized aphids. Learn to recognize aphid “mummies,” as they indicate the presence of tiny parasitic wasps that lay eggs inside the aphids. The wasp larva hatches and feeds inside the aphid, killing it. The skin of dead aphids turns crusty and golden brown or black, a form called a mummy. Not long after, the adult wasp chews an exit hole and emerges from the aphid's body. During warm weather, parasitic wasps may have several generations and cause a rapid decline in aphid populations.
There are fungus diseases that infect aphids, especially when it's warm and humid. Entire populations of aphids may be killed when conditions are right. While aphids thrive under mild temperatures, populations of many species are reduced by hot summer weather conditions. If you have any of these natural controls at work, the aphid population may crash rapidly.
You may be able to control aphids in your trees by controlling ants. If large numbers of ants are seen climbing up and down tree trunks, it may mean an aphid infestation. Ants are attracted to the honeydew produced by the aphids. If you plan to use pesticides for ant control, first seek out and treat the ants' nests in the ground near the tree. Or, place sticky barriers around the tree trunk to keep the ants from reaching the aphids. Unprotected by the ants, the aphids may then be attacked by natural enemies.
You can help prevent aphid infestations, especially in vegetables, by removing weeds where aphids may be building up. Also, check transplants for aphids and remove them before planting. If you notice a few curled leaves on your fruit trees, the best control may be to simply prune out and dispose of the infested shoots and leaves.