By Theresa Knutsen
Topics covered in the July Growing Tips:
Including install spreaders, tie in espalier branches, manage blackberries, clean up spent strawberries and raspberries, control weeds, protect ripening fruit from birds, support limbs and thin heavy fruit set, inspect for problems
Container Plants Care (watering and fertilizer)
My new plant has leafed out but has not grown any new shoots, will it be OK?
Summer is an insect time of year. Some are prevalent everywhere (aphids, spider mites, mealy bugs), others may be more locally specific (types of scale or fruit fly). Monitor your plants regularly; look for changes in leaves (top and bottom of leaves) or fruit, unusual bumps on stems, ant trails in your plants, etc. Use insect monitoring traps for some that are more difficult to see. Refer to the Raintree Nursery Owner’s Manual, your local co-operative extension service or state agricultural university, Oregon State University, California State University, or Cornell University, for help in identifying and controlling insects in your plants. The earlier you notice an infestation the easier it may be to control.
Spotted Wing Drosophila, Drosophila Suzuki, is a new pest of concern along the west coast of the United States. First identified in California in 2009, it has since then been identified north to B.C. Canada in many areas along the I-5 corridor. Hot dry summers are expected to limit its spread into the interior portions of the country. It is a type of fruit fly, or vinegar fly is another common name. Unlike other types of vinegar fly which deposit their eggs in fully ripe fruit, this one deposits her eggs in the fruit just prior to the full ripe stage. The larvae are mature and ready to pupate in 6-10 days, when the fruit is just ripe and ready to pick, depending on temperature. This fruit fly infests many types of soft fruit, from blueberries to strawberries, domestic or wild, and many others in between. At this point the insect is not widespread, but is expected to become more established over the next few years. Learning to monitor and identify this insect will be your first best step to dealing with it. Currently, Spinosyn based insecticides are the recommended spray if they are present in your fruit plantings. Oregon State University is providing a central web page for people in the Pacific Northwest to learn more about the life cycle, identification, and monitoring of the Spotted wing drosophila, at spottedwing.org. Their information had become oriented more toward the commercial grower though. Contact your local co-operative extension service for information on back yard monitoring and control, or to see if the SWD fruit fly has been reported in your area. SWD is also present on the east coast, Cornell University has a helpful web page; http://www.fruit.cornell.edu/spottedwing/index.html.
Monitor both apple maggot and codling moth traps to determine when insect populations are increasing throughout the fruit development season, so you can apply control measures when they are needed and will be most effective. Surround and other types of insecticidal sprays will need to be re-applied periodically throughout the fruit ripening season. Read package labels for instructions.
Apple maggot control bags only need to be installed once. Just install them by the time the fruit is nickel size for season long prevention of egg deposit by apple maggot flies. Thinning the fruit at the same time will reduce the total number of bags you need to install, and allow the fruit to grow to a larger size. The newer, heavier duty nylon apple maggot control bags we are now offering may also be effective against codling moth, if installed before eggs hatch. See the May Growing Tips for a recipe using Surround to improve codling moth control with apple maggot control bags. A paper type bag is effective, but will need to be removed for the last couple of weeks before harvest to allow color development of the fruit.
There are other non-chemical techniques you can also include in your control program. Sanitation is one of the most important, for both apple maggot and codling moth control. Every week or two, beginning about 6 to 8 weeks after bloom, check fruit on trees for signs of damage. Look for pin-hole scars (where apple maggot eggs have been deposited) or slightly larger scars where the codling moth caterpillar chewed its way in (sometimes not very visible because it went through the blossom scar). As the caterpillar grows it pushes its “frass” (excrement) out of its entrance hole. Remove and destroy any visibly infested fruit before the larvae are old enough to crawl out and begin the next generation. This can be a very effective method for reducing the insect population, provided your orchard is relatively isolated. If your neighbors are not taking care of their trees, you may have to take additional steps. Also clean up dropped fruit as soon as possible after they fall because dropped fruit may have larvae in them. Removing infested fruit from the tree and promptly picking up dropped fruit from the ground is most critical in May and June, but should continue throughout the season.
Install more codling moth and apple maggot traps than are necessary to observe population fluctuations to trap more individual insects and help reduce total populations. Be careful with how many codling moth pheromone lures you install though. In large orchards, placed around the perimeter, extra lures effectively contribute to controlling the codling moth. In small orchards, extra lures have been shown to increase the number of adult moths and level of fruit damage.
Spinosad, and other spinosyn based sprays, is a broad spectrum natural insecticide derived from the metabolites of a common soil bacterium. It is effective against codling moth, plum curculio, and currant worm caterpillars before they enter the fruit. Apply the first spray 2-4 weeks after bloom, or when you start seeing the pin hole scars. Start looking for the scars a week or so after catching increased numbers of adults in your monitoring traps. Reapply Spinosad every 10-14 days, up to 6 times per year, following label instructions. New adult populations can emerge periodically throughout the growing season, up to 3-6 times depending on the insect and the length of your growing season.
Some varieties of grapes, apples, gooseberry, currants and other fruits are susceptible to powdery mildew. There are chemical fungicide sprays available at your local nursery, or you may want to try the recipe on page 22 in our Raintree Owner’s manual. You can achieve a reasonable level of control using fatty-acid soap, oil (such as Neem), and powdered milk, but you will have to apply repeated sprays throughout the typical infection period, from June through August or September. To avoid having to spray choose varieties listed as being resistant or immune to powdery mildew.
Some varieties of grape produce clusters of berries that are very tight, which can be susceptible to botrytis (bunch rot). Thin fruit clusters to maintain better air circulation in the bunch. Serenade, a biological fungicide derived from Bacillus subtilis strain, may be effective as a spray. Botrytis also affects other fruits, including strawberry, raspberry, blackberry, blueberry, cherry, and pear. Keeping the fruit dry, and not in contact with other fruit will help minimize spread of the disease. Sanitation is very important. Clean up and discard infected fruit (compost piles are generally not hot enough to destroy the organism), as well as old leaves that have died back or have fungal lesions on them, to remove as much source of inoculum as you can.
If you have anthracnose lesions in the bark of your apple tree you can cauterize or excise new infections once the weather has dried out. To cauterize use a hand torch with a small flame, heat the bark until it begins to bubble, be sure to stop before it begins to turn black. Your goal is to cause heated cells to expand and rupture, not burn them. Apply heat to the entire lesion area, as well as about ¼” outside the lesion all the way around, to make sure you have destroyed all of the fungal organism. To excise the lesion, use a sharp blade, such as a utility blade or a grafting knife. Start at a point above the lesion about ¼” and press just hard enough to cut through the entire bark layer. Make an oval shaped cut with a point at the top and bottom around the lesion, about ¼” away, then pop or pry out the piece you have cut loose. Keep the pieces as you remove them so you can burn them and destroy the fungus when you are done. Clean the blade between each lesion with alcohol. Either cauterize or excise as early in the summer as you can to give the tree plenty of time to heal over the wounds.
Summer has arrived, the lush growth of spring and early summer surrounds us; here are some tips to guide that growth where you want it:
Put spreaders in narrow crotches of well placed new shoots on your young fruit trees. A wooden clothes pin is effective for smaller shoots, the 4” pointed spreader T610 will work for branches larger than ½”. A sandwich bag of sand or rocks tied to the branch just far enough out its length to pull it down also works well. An ideal angle is about 30-50° from the main trunk.
Remove suckers growing from the rootstock on younger trees.
Tie in growing branches on your espalier to keep them in your desired form as you develop the new tree. Remember to allow shoot tips to remain pointed up when you are training horizontal branches in the espalier until the branch has extended to the desired length.
Maintain a more compact size in your upright growing blackberries, such as Apache or Triple Crown. When the new shoots have grown to your desired height (4-6’) snip out the growing tip. This will encourage lateral branching that you can cut back to 2’ next winter. Don't delay! Waiting until later reduces the number of laterals that will develop, and how long they will grow.
Trailing blackberries will be sending up their new canes as well. Train them on the wires, preferably next to, rather than mixed up with, the current year fruiting canes. I like training them on two wires strung about 2.5-3’ apart vertically on the posts. Coil the canes over the topwire, under the bottom wire, and continue in a spiral fashion. Train one year’s growth going one direction (i.e. left) and the next year’s growth going the opposite direction (i.e. right). Another method is to train them on a 6-7’ high mesh with 6-8" holes, such as concrete reinforcing wire. With this method plants can be spaced at about 4-5’ apart, and each season the canes are trained vertically (weave through the mesh) in a 2-21/2’ wide swath up and over, separate from the previous years’ canes. If the cane tips start reaching for the ground either prune them back or bend them back upwards to prevent unwanted rooting.
Cut off old leaves and unwanted runners of summer-fruiting strawberries after the last of the fruit has been harvested, or mow with the lawn mower set in the high position. Burn the leaves and runners with the straw and weeds to control the spread of fungal disease.
When summer-bearing raspberries have finished fruiting remove the spent canes to make room for this season’s new canes.
Control weeds and keep grass short around bushes and trees and among recently planted ground covers. Maintain a minimum 3’ diameter circle for each tree or shrub that is free of competing weeds. If there are a lot of weeds coming up in your new groundcover planting, lay multiple layers of newspaper, or a layer of cardboard, between plants to smother weeds and retain soil moisture. A layer of bark or compost on top will keep the area looking nice. Invasive perennial weeds, such as quack grass, ivy, or morning glory will not be controlled as readily in one year with smothering. Avoid using broadleaf herbicides or weed and feed products near your new plants, they can cause significant damage or even death.
Protect ripening fruit from birds. Protect fruit trees (up to 10’ wide) or grape vines with our 22' wide heavy duty Bird Netting (#T431). Construct a cage for berry bushes to support the wide bird netting or drape with the lighter weight black nylon mesh. Close the netting securely under the plant canopy to keep birds from sneaking under. Bird scare tape, a shiny metallic ribbon, will help deter birds from munching on your fruit when the flashy movement in the wind startles the birds.
Support heavily laden branches of your fruit trees to prevent breakage of main limbs (fruit weight plus a bit of wind can cause a lot of damage). Thin the fruit from the terminal end of the branch to reduce leverage that could cause damage. Over bearing of fruit can result in an excess energy drain on the tree. The tree may then set fewer flower buds for the next year, to allow time to recover from the heavy energy out put. Thinning the fruit, by the early part of the summer, will increase the size of the remaining fruit and prevent excess energy drain on the tree. Thin to leave 1 fruit every 6-9" along the length of the branch, the greater distance at the end of limbs, or during droughty summers. Thinning out heavily weighted dangling limbs will help strengthen the remaining branches, de-weight them (prune back to an upward growing shoot) so they move upwards to a more desirable angle, and thin excess fruit.
Do not tie ropes or chains around tree trunks when you stake them. They can cause serious damage by chafing and constricting the trunk. Monitor newly planted trees and remove staking as soon as the support is no longer needed.
Inspect your fruiting plants; look for dead or broken branches, changes in leaf appearance (raised bumps, color other than green, fuzzy or warty growths), ant trails in your trees or shrubs, etc., to help catch problems while they are still treatable. If you are not sure if what you are seeing is a problem contact your local co-operative extension service for assistance in identification, or publications with identification and control information, or your state agricultural university. Oregon State University, California State University, Texas A&M, and Cornell University have excellent web sites to help you with identification of the typical pests and diseases in their areas. See Useful Links in Gowers Info (top tool bar) to find your local co-operative extension service web site.
Are you planning to do some bud grafts this summer? Keep rootstocks watered and growing. They need to be actively growing in August when it is time to do your grafts. Check bench grafts or spring buds you completed 6 or more weeks ago, it is probably time to remove bands. If you did spring bud grafts it will be time to start cutting the rootstock back about 4-6 weeks after the graft. You can cut the entire top back at once for most types of fruit, some prefer less shock by cutting the rootstock back in two stages, a few weeks apart.
Adjust water rates as necessary to keep up with plant demand without keeping the soil constantly saturated. Always check the soil 4-6” deep, rather than on the surface, before irrigating. A finger poked into the ground does not sense wet or dry well, but does sense temperature. If the soil feels quite cool relative to the air temperature there is probably plenty of moisture in the soil, if it feels warm, or close to the air temperature, it probably needs water. Newly planted trees and shrubs will benefit from regular irrigation, especially during the dry part of summer, until their roots are well established. Plan on providing irrigation at least the first year or two. A drip irrigation system will provide water efficiently to help your new plants establish and grow well in their first two years.
Trees and shrubs, keep pruning light this time of year, removing no more than ¼ of the live branches. Thin out water sprout wood before it gets very big, unless you are planning to collect some scion wood for grafting. Summer pruning has a dwarfing effect and is useful in controlling the size of trees that tend to get too big.
Prune vigorous grape shoots (3-4' or more extension past the last fruit cluster) at 5-6 leaves past the last fruit cluster to keep the vine a manageable size and allow more sun onto the developing fruit. If you are using a cane replacement system and your replacement canes are initiating side branches, cut those side branches back to one leaf. Tie canes onto the support system as needed to keep them from flopping around. Thin out some of the leaves around the fruit clusters to allow more light in. On a mature vine thin out unproductive shoots.
TIPS FOR ESPALIER: Fruits trained as a cordon, espalier or dwarf pyramid (3-dimensional espalier) are best pruned in the summer to keep unwanted vigorous shoots controlled. If you keep up with the summer pruning, you won’t have to do any winter pruning, except winter damage. In all espalier forms remove unwanted vigorous shoots at the point of origin.
For apples, pears and other long-lived spur type fruits, vigorous shoots arising where you would like to have a fruit spur can be convinced to produce fruit buds by slowing down their vigor. Here at Raintree it has worked well for me to cut those vigorous shoots back to six inches when they are about 8-12” long. Over the rest of the summer regularly cut back to a couple leaves the new growth that arises from the top several buds of that shoot to reduce its vigor. Then in early fall you can cut the shoots back to the fruit buds that have formed near the base. You may need to use a different method where you garden; your local climate has an impact on how trees respond to pruning. Lee Reich’s book “The Pruning Book” (#S327) has an excellent section on how trees respond to pruning, in addition to an espalier pruning section. Pruning and Training Revised, by Brickell and Joyce (#S325) uses line drawings to illustrate each seasons tasks and is based on the modified Lorette system of espalier pruning that works well in England.
Cut back laterals on fan-trained sweet and Duke cherries that are not needed for the framework to six leaves in late July. Pinch out the tip of vigorous laterals on fan-trained peaches at 18” to encourage small laterals for next years fruit production. Pinch out the tips of new shoots not wanted for the framework of fan-trained plums when they have made 6-7 leaves to develop fruit spurs. Refer to Pruning and Training Revised for more specifics on training espalier form fruit trees and bushes.
Potted plants can be planted out, with care, if the temperatures are not above the mid-80’s. Otherwise, maintain your potted plants in a location that provides as much sun as they will tolerate, (some may need partial shade) until summer weather has moderated and you can plant. If your area has warmed up above 80 deg. we will be shipping potted plants again in October, an excellent time for planting if you live in a USDA Zone 6 or warmer area. In the mean time, make a plan of where you want to plant new fruit trees and shrubs, and prepare a planting hole. Loosen the ground with a digging fork or shovel, and start sheet mulching with cardboard or several layers of newspaper. Then apply alternating layers of straw or leaves and grass clippings, to smother weeds and build the soil for your fall or spring planting.
Prepare new strawberry beds and plant out runners you collected when cleaning up your existing patch.
Enjoy brambles (blackberries and raspberries), July bearing strawberries, currants, gooseberries, cherries, early peaches, asian plums, apricots, early euopean pears, and early ripening Raintree Select goumi. Everbearing strawberries are starting to ripen, and will continue to provide fresh berries through fall. I like to harvest my currants with a lingonberry rake, (#T300), to get the job done neatly and quickly. Hold the shoot upright with one hand, and rake along the fruit racemes from bottom to top. This year I learned a neat trick to help clean up those small sized currant berries. After harvesting put the berries in a thin layer on a cookie sheet, or half fill a freezer bag, and pop them in the freezer. Once frozen you can readily separate the hard berries from the stems, a bit of a rinse and they are ready for processing! Our recipe page gives you basic instructions to make juice and jelly from scratch. To reduce the amount of sugar in my fruit I am planning to mix a bit of applesauce with pureed currants this year, and then make fruit leather. The tart flavored leather, torn up in pieces, will make a lively addition to a gift bag of mixed dried fruits.
Summer is in full swing and plants are in active growth. Water often enough to keep plants from wilting with water stress, but not so much that roots start to rot from lack of oxygen. Water needs will vary from one plant to another. A small plant in a large pot does not remove very much water from the soil, so it is easier to over water and rot the roots. A large established plant dries out more easily because the soil does not hold as much water and the plant roots extract more. Check for soil moisture several inches under the surface, using the same technique described in the irrigation section above; or lift or tip the pot up to see how much it weighs. Allow citrus and stevia (sugar leaf) to dry out somewhat between each watering, but keep figs and bamboo evenly moist. If plants regularly wilt in the afternoon but the container always seems to have enough moisture in it move the container so it is protected from the late afternoon sun. Remember plants may also wilt if the soil is kept constantly saturated and the roots are starting to rot, in which case allow the soil to dry out before watering again.
New plants that started the season with a slow-release fertilizer are probably ready for a booster now. The frequent watering that is required to keep the container moist leaches nutrients from the soil. Fertilize regularly with an appropriate type of fertilizer for what you are growing. Some plants have specialized needs, such as citrus or blueberries. For best results use a fertilizer that indicates it is for the particular type of plant you are growing on the label.
Citrus trees may send up a few overly vigorous shoots, trim these back to where you would like to see branching to keep your plants more compact, or thin them out if they are not needed in your tree. Rootstocks may send up suckers also, remove them completely to keep the energy focused on your variety.
Sugar Leaf (Stevia ) will send up flower stems as the day length decreases. Harvest leaves just before the buds open for highest sugar content, cutting plants back to about 6" so they can regrow. Keep the soil moist but not constantly saturated. Use a vegetable plant or fish fertilizer for balanced growth and best flavor.
Vines and ground covers can offer tasty treats for the eye as well as the palate. Grape and kiwi vines with wonderful fruit, some with beautiful foliage color or texture, can be trained over sturdy arbors as ornamental features. Some strawberries produce fruit throughout the summer and into fall for a tasty ground cover; cover a south or west facing slope with heat loving tristar strawberries, or choose alpine strawberries with a clumping habit and no runners. Plant wintergreen for its aromatic red berries that persist well into winter on a low mounding shiny evergreen plant. Grow a patch of Lingonberry in a well-drained sunny location and harvest the berries just in time to make a delectable sauce for your thanksgiving turkey.
My new plant has leafed out but has not grown any new shoots, will it be OK? It can be OK. Branch extension occurs when the roots start growing. Sometimes the growth in the top of the tree gets ahead of the root system, such as when bare root plants are planted late in the spring when day time temperatures are averaging above 75° F and the soil is still cool. To help the tree re-establish balance provide the plant with shade (put up a simple framework and drape with burlap, shade cloth, or attach lath screens to provide 50% shade), or mist the foliage regularly to reduce water demand in the plants until the roots are growing well. Keep the soil evenly moist, but not constantly saturated. Excess water remaining in the root zone area keeps the soil cool and pushes oxygen out of the soil, which roots need to breathe and grow.