By Theresa Knutsen
Potted plants are preferable for planting in the ground once summer temperatures arrive. In locations where summer has not yet arrived you can also plant our bare root plants that have been kept dormant in cold storage and are still available. However, even in the cooler more northern locations, where spring still prevails, summer temperatures can come quickly. If your day time temperatures will be 75- 80° F (or more) within the first few weeks following planting you will need to take special precautions to ensure success with your new plants, particularly the bare root. (Or you may choose to call us and pre-order bare root plants to be shipped to you at your optimal planting time next year). For best results follow our hot weather planting instructions, Plant Owners Manual, pg 2, or the following:
If you choose to plant in the ground in a permanent location right away; soak the roots in water 1-2 hours just before planting, mulch the soil surface well after planting, irrigate regularly to keep the soil evenly moist, not soppy wet, and provide shade until the plants are well-established. Warmer air temperatures encourage faster shoot growth than root growth, creating water stress in the tree; shade helps to reduce the water needs of the plant and give the root system time to catch up with the top of the plant. Instead of providing shade, another technique you can use, taught to us by a Southern California grower, is to whitewash the dormant tree before planting out. Use a 50/50 mixture of white interior latex paint and water, and apply to the entire tree above the roots. If you use a brush, apply it with an upwards motion, so you do not knock off the buds. When the paint is dry, follow the rest of the planting instructions above. The buds will be delayed a little bit, and the trunk and branches will stay cooler, giving the roots some time to start growing and doing their job before the leaves start demanding water and nutrients.
Or you may choose to plant your new plants in the ground in a temporary, shady location. Mulch and water them regularly through the summer. In the fall, when the worst of the summer heat has passed, dig and move the plants to their permanent location. By the following spring they will be well-established and ready to grow.
A third choice is to plant your new bare root plants into containers. Maintain your potted plants in a protected location until established, and plant in their permanent location in the fall when the worst of the summer heat has passed.
Our potted plants have been held in a greenhouse and are out of dormancy now, so will benefit from hardening off before planting out. Expose the plants to indirect sun for a few hours the first day, then gradually increase the number of hours and the amount of direct sun over the next few days to get then used to direct sun and wind. If you prefer to wait until fall to plant your potted plants in a permanent location they would probably benefit from potting up to a slightly larger container. 4" to 1 gallon, 1 gallon to 3-5 gallon (depending on vigor).
The calendar suggests that summer is approaching, and day time temperatures do seem to be gradually warming here at Raintree Nursery. With the warming of summer comes a myriad of insects ready to infest our favorite fruiting plants. Take a pro-active stance by monitoring. Install traps or regularly inspect your plants for insects such as: fruit infesting-apple maggot, codling moth, Spotted wing Drosophila; leaf and stem infesting- aphid, spider mite, imported currant worm, thrips, white fly, leaf hoppers, and mealy bug. Take samples of insects to your local co-operative extension service for help identifying what's 'bugging' you. To find your local extension office go to Growing Info in the top tool bar and select Useful Links under More Growing Info.
Apple maggot and codling moth: Continue monitoring both apple maggot and codling moth traps to determine when populations are increasing, so you can apply control measures when they are needed and will be most effective. Both insects could be in active flight now in the Pacific Northwest.
If you don’t want to spray, apple maggot control bags only need to be installed once. Just install them by the time the fruit is nickel size for season long th 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. To install the apple maggot control bag stretch the top inch or so open, slip it over a fruit, then twist and snugly wrap the neck of the bag around the fruit stem to secure.
Go to the May Growing Tips Insect/Disease section for more details on apple maggot and codling moth monitoring and control (Click on Growing Info on our home page, scroll down to find May Growing Tips).
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 now 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, Spinosad insecticides are the recommended spray if they are present in your fruit plantings. Go to this web page to learn more about the life cycle, identification, and monitoring of SWD (Spotted Wing Drosophila) https://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/20883/em9026.pdf.
Contact your local co-operative extension service to see if the SWD fruit fly has been reported in your area or more local information is available.
As the weather warms up aphid and spider mite insects start coming out. Monitor your fruit trees and bushes for evidence of insects ready to rapidly increase in number. Leaves with edges rolled down and yellow or red bumps on top often have aphids on the bottom side. Check for ants moving up and down the plants, which might be protecting (farming) the aphids. Yellow stipling (tiny yellow dots) visible from the top of the leaf, or fine white webbing on the underneath side of the leaf are good indicators that spider mites are present. See our Raintree Plant Owners Manual, pg 16-22, for control recommendations.
If you have gooseberry, or red or white currant, it is time to monitor for the presence of the imported currant worm. The white eggs are deposited by the female sawfly on the underneath side of leaves near the bottom center of the bush, late May or early June in the pacific Northwest. The small green caterpillars eat the leaves, moving through the bush in an upward and outward pattern. Often, they are not noticed until the bush appears to be suddenly defoliated. Check now for the white eggs, or the new small caterpillars feeding along the edge of a leaf (look close, they blend in easily) near the bottom center of the bush. When the small caterpillars are present use Bt spray to control, or insecticidal soap with neem oil. Years ago I found that ducks are useful for controlling the imported currant worm. The female sawfly usually went to my Jostaberry bushes first to deposit her eggs. One day I noticed my ducks enjoying themselves under the Jostaberry, where the new caterpillars were right at their eye level. I moved the Jostaberries into the duck yard, and did not see any more caterpillars in my bushes until the ducks were gone (too many predators). Even if you don’t want to raise ducks, plant a Jostaberry (#E770) as a trap crop to check for the caterpillars first.
Throughout the summer continue monitoring for the presence of aphids, scale, spider mites, thrips, white fly, and mealybug. All of these soft-bodied insects can be controlled with fatty-acid soap sprays (insecticidal soaps).
Weather patterns in the Pacific Northwest typically provide good conditions for fungal diseases to prosper in our fruiting plants, and this year was no exception. Our November and December freezes could have caused physical damage in plants that had not achieved full dormancy, and our usual alternating warming/freezing winter and spring pattern could have contributed as well. Fungal and bacterial diseases often then establish in damaged tissues and prosper during our typical cool wet spring.
Continue apple and pear scab control sprays, until summer weather settles in. Our typical cool wet spring in the Pacific Northwest provides just the right conditions for scab to grow and prosper.
Some varieties of grapes, apples, gooseberry, currants and other fruits are susceptible to powdery mildew. There are chemical 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 (insecticidal soap), oil (such as Neem), and powdered milk, but you will have to apply repeat 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.
In the Pacific Northwest, if you are seeing die back and blackening of stems in your Asian pears this year most likely they are infected with pseudomonas disease, an opportunistic bacterial disease. Pseudomonas can also affect stressed European pear or apples. Symptoms may resemble fireblight, but often occur at a different time than fire blight symptoms. Once the weather has warmed and dried you can prune out affected areas. A fixed copper spray applied in the fall and early spring will help prevent infections if you see this kind of damage every year.
Monitor your orchard for early signs of bark disease in your fruit trees. Anthracnose infects apple trees, and bacterial canker causes bark lesions in stone fruits.
Anthracnose looks like small, circular to oval, reddish brown areas on the bark that extend to the underlying tissue. Use a clean knife to cut into a potentially infected area to see if there is brown under the surface layer. By summer the infected bark dries out and appears stringy over a concave wound beneath it. Copper sprays applied before fall rains and again after leaf fall are helpful. Remove heavily infected trees and burn them, remove heavily infected limbs or branches if the expression is more localized on the tree.
Bacterial Canker lesions in stone fruits are usually associated with amber colored gum production, will be soft under the gummosis, and tissue under the canker will be discolored. Infections also occur in buds and on leaves. Major infections can girdle a limb. Infections often occur where there has been physical damage from early hard freeze or late frosts. Copper sprays applied before fall rains and again in early January are helpful.
Cauterize individual canker sites of both bacterial canker and anthracnose by heating with a small torch only until the surface bubbles. If it starts to turn black you have overheated the area. Treat the entire infection plus 1/4 inch beyond its perimeter, making a pointed oval shape.
Cut out individual canker sites of both bacterial canker and anthracnose with a clean sharp knife, cutting to the cambium layer. Remove the entire infection area plus 1/4 inch beyond its perimeter, making a pointed oval shape. Burn or destroy the piece you remove.
Nectria Twig Blight, Nectria cinnabarina, occurs in apple, pear, plum and maples in our region, as well as alder, rhododendrons, hydrangea and daphne. The fungus is present and grows without symptoms on woody trees, and then invades the wood after an injury occurs, such as freeze, pruning, or limb breakage. Symptoms can develop when the tree is under stress, such as drought. On infected wood irregular shaped sunken areas develop under discolored bark., often near a pruning cut. If a canker girdles a stem you will see sudden wilting or lack of leaf growth in the spring. Coral colored fruiting bodies appear on infected wood or bark during the spring or summer, eventually turning black the following winter. In summer and fall a different type of fruiting body may appear which is dark red in color. There are no chemical controls recommended. Cultural controls include keeping pruning stubs short and removing infected limbs. Avoid spreading Nectria spores by sanitizing your pruning tools often with alcohol or a mild bleach solution if you are working in known or suspected infected trees.
For more information on insect or disease control in your area contact your local co-operative extension service. They should be able to help you identify what your problem is and have a bulletin or hand out you can acquire with control information. Refer to our Useful Links page in 'Growing Info', go to our home page to find the Growing Info link.
Pruning and training fruit trees and berries is an on-going process through most of the year. Here are some tips for blackberries, grapes, strawberries, fruit trees, currants and gooseberries.
Train new shoots of blackberries: Coil new shoots of trailing type blackberries over and under 2 wires (over the top and under the bottom) positioned about 2 -2 ½ feet apart vertically. Coil in one direction one year, the opposite direction the next year, to make it easier to harvest fruit and clean up spent canes. Vigorous upright blackberries can be tip pruned when they have grown to about 4-6’ (the height is your choice). Tip pruning while the cane is actively growing encourages lateral branching. Tip pruning during the winter just makes the cane shorter. During winter prune the laterals back to about 2’ long, leaving a 4’ wide bush ready to produce loads of berries for you.
Grapes, thin unproductive shoots, position and train remaining shoots. You can also shorten long fruiting shoots as the summer progresses, leaving 5 leaves past the last cluster of fruits that set. There are many training systems for grapes, ‘The Grape Grower’ (#S185) has instructions for many of the possible training systems. In the Pacific Northwest, where getting as much heat as possible to the ripening fruit is very important, new training systems have been trialed at Mt Vernon research station. We describe the vertical 'Curtain' training system in the Raintree Owners Manual.
Remove runners from strawberries to keep plant energy directed to producing flowers and fruit. Select and position some runners, if needed, to fill in the row.
Remove unwanted suckers in fruit trees while small by rubbing them off, particularly where lots of heading cuts were made in the tops of trees, or along the top of more horizontal branches that have plenty of fruit spurs. Also look for and remove suckers growing from the rootstock below the graft. If you have not finished pruning your fruit trees you can still work on them. Once your fruit trees are past the first flush of growth in the spring thinning cuts will help keep the trees opened up without triggering vigorous new vegetative growth.
Cut back laterals on red and white currant and gooseberry cordons and bushes (from late June to early July). Pinch out the growing points of selected shoots on established fan-trained plums and apricots (until late July). Pinch out selected growing points on cropping fan-trained figs. The book ‘Pruning and Training revised edition’ by Christopher Brickell and David Joyce available through on-line sources, has illustrations to help you know where to make these pruning cuts.
Observation is your number one tool in maintaining and enjoying healthy plants. Be on the lookout for the usual issues you see in your location, learn when it is time to look for and see first infestations of disease or insects where you live. You may find resources in our Raintree Plant Owners Manual calender, pg23-24, our Useful Links page, or from your local co-operative extension office. Also keep your eyes open for new surprises. Here are a few things I’ve noticed at home this spring. My peach tree is not coming out of dormancy with vigor (probably a mixture of leaf and bud blights caused by winter's hard freeze and cool wet conditions during bloom this spring followed by fungal disease infections). Thatching ants are chewing on my rhubarb, where the leaf blade meets the stems, which can result in death of my younger plants. I am also seeing ants in many of my fruit trees. Blueberry leaves are more purple than green, indicating the root systems are not picking up nutrients properly. If this was mid-summer I would be concerned about pH, while the soil is cold and wet in the spring however the plant roots have a more difficult time picking up nutrients and the foliage often will be off color. If I don’t see improvement a little liquid fertilizer for acid loving plants will perk up my blueberries. Both at home and here at Raintree Nursery I have not seen much bee activity this spring, honey or mason bees. I am also not seeing much evidence of fruit set this year, I will continue to monitor. Last year's heavy fruit set resulted in a fair amount of limb breakage, proper thinning of the fruit would have reduced or eliminated the tree damage.
Mow, keep grass short and weeds under control. Avoid hand digging of weeds under blueberries, their roots are shallow and easily damaged. Sheet mulching is an effective way to reduce weeds without damaging shallow roots. Put a 1-2” layer of compost or organic material on the surface, a layer of newspaper (several sheets) or cardboard, and then wood chips or bark, not to exceed 4-5 inches total.
Weed killers can be harmful to your fruiting plants. Avoid using broadcast weed and feed lawn products within the root zone area of your fruit trees, which can be harmed by the herbicides when they soak into the ground. The typical spread of an established trees root system is 3-5 times the width of the canopy, with the most active part starting at about the edge of the leaf canopy and extending outward about ½ the width of the tree. Spray drift from glyphosate (in Roundup and other products) can cause dieback, stress, or death when it lands on and penetrates into thin bark. It can also cause bark lesions in stone fruits if absorbed through the roots. Symptoms may not be present until the following year. The pre-emergent herbicide dichlorbenil (in Casoron) leads to stunted yellow leaves and death if over-applied or used repeatedly.
Thin fruit of peaches, nectarines, apricots, plums, gooseberries, apples and pears before the June drop. Fruiting plants will naturally shed surplus fruit to maintain a healthy energy balance in the tree. If you remove a bit more fruit than the plant would normally shed, the remaining fruit will tend to be larger. Also, you can reduce the tendency for a tree to have alternate bearing years by evening out the crop each year. Thinning should be completed before the tree would naturally drop its fruit, or before the end of June in the Pacific Northwest.
Install bird netting to keep birds out of your favorite fruits if they were a problem for you last year. The small mesh black netting is useful over strawberries, blueberries, and other small sized plants or bushes. For larger fruit trees or grapes we offer 17’ wide medium weight commercial netting (#T432) and 22' wide heavy duty commercial netting (#T431) that will allow you to cover a tree or trellis with one piece.
Spray apples against bitter pit in mid-June if you saw symptoms last year in your fruit. Bitter pit symptoms are circular or slightly irregular depressed spots on the fruit surface, with brownish or streaked off-color areas under the depression in the meat of the fruit. Pits are usually more numerous on the blossom end of the fruit, and can show up before or after harvest. Bitter pit is a physiological disorder, not a disease, caused by in-sufficient calcium available during fruit development. Hot, dry weather in July and August, irregular irrigation, heavy dormant season pruning, over thinning of fruit, and excessive nitrogen fertilizer can all contribute to an in-balance of calcium in the tree, resulting in bitter pit symptoms. Calcium chloride or calcium nitrate sprays may help correct an imbalance in the fruit, follow the instructions on the package.
Water all plants to provide 1” of water each week if mother nature does not do so with rain fall; or enough to keep the soil evenly moist to about 12" deep, but not constantly saturated. For a 3' diameter planting hole that would be 10 gal's of water. Newly planted trees and shrubs will benefit from regular irrigation, especially during the dry part of summer, until their roots are well established. Deep watering 1-2 times per week is more effective, and better for the plants, than shallow daily watering. 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.
Blue Honeysuckle fruit are often ready to eat in early June. In the warmer parts of the Pacific Northwest currants and early brambles may be ready to harvest this month. June strawberries should be picking soon, but this year's wet spring pattern may lead to the presence of fungal disease in the fruit. If our more typical cool, wet spring seems to encourage fungal disease in your strawberries most years, you might consider trying a variety that ripens just a little later, such as Puget Crimson (#E406) or Puget Summer (#E405). Day-neutral varieties will produce all summer, keeping the strawberry shortcake desserts on the menu into fall. Read more about our strawberries to determine which ones will work best for you.
Water and fertilize regularly to keep up with the needs of actively growing plants. Allow citrus 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.
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. A whitwash of 50% interior latex paint/ 50% water applied at planting time when a tree is still dormant also helps reduce heat stress in the tree. 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.
When will my new fruit tree produce fruit? Most of our fruit trees will start producing fruit in their third summer. In some cases there may be some fruit in the first or second year. It is best for the health and long-term vigor of your new tree that any fruit that starts to grow in the first two years be removed. This allows the tree to focus the available energy on growing strong roots, trunk, and primary scaffolding branches, instead of energy demanding fruit. Often, if the tree is allowed to ripen fruit during the first two years, it will be several years before it flowers again.
Native plant species are essential for providing butterfly and hummingbird habitats. Add some of these for their nectar, as well as food sources for caterpillars. Elderberry; Sambucus cerulean, S. racemosa, S. canadensis. Huckleberry; V. ovatum and V. parvifolium. Kinnikinnik, Red Flowering Currant, Salal, Serviceberry, Amelanchier alnifolia.
Some natives can be used in ornamental containers as effectively as common ornamentals, combined with other plants with similar requirements or by themselves. Kinnikinnick will drape nicely over the edge of pots. Evergreen or Red huckleberry will make a lovely specimen container alone or combined with ferns.