Strawberries Slide 1 Strawberry production in the home garden. Slide 2 Western Washington has long been a strawberry production area. The fruit from western Washington is typically juicy, very flavorful, and highly aromatic. However, the fruit is soft and does not keep in storage very well. Over time the fruit was primarily processed, but with a decline in processors in the past several years, more and more fruit has been used for the fresh market. California has increased production considerably over the past several years. Locally, most of our competition comes from California that produces much firmer berries and can be shipped and stored for extended periods of time. Slide 3 June-bearing strawberries are very popular in the home garden and are the most widely grown commercial variety of strawberries in the area. Here we have, in late September, a popular variety of June bearing, showing the nice deep green lush growth. These plants are traditionally renovated after harvest, where we will come in and mow these a few inches above the crown to remove a good share of the old leaves and have those composted or tilled back into the soil. At that point we can look at the density of the plants. Quite often these plants will be planted as much as two feet apart. We are going to get smaller plants that are going to take that space between our two original plants, such as, here's one that started from a runner, here is another one that started from a runner, here is another one. And you can soon see that twenty-four inches apart soon becomes a plant every five to seven inches. After the renovation the plants will grow new leaves. At renovation time, because you can see the spacing of the plant, it's a good time to look at the density of plants, it's a good time to fertilize, to get water on the plants because at that time in August these plants respond to shorter day lengths, and that sends a trigger to the plant to start producing or setting fruit buds, flower buds, for next year s crop even though it's ten months away. So you want to make sure and get some fertilizer on the June bearing varieties and some water on the June bearing varieties during August. If you're on vacation, don't ignore the plants or neglect the plants because next summer, if you have a poor crop, you're going to blame it on next summer's weather or the spring pollination time, but it may actually be what you did or didn't do to the plants that previous summer. You can see how nice and green those new leaves are, free of insects, diseases. A well-weeded patch, just what you'd want to see going into the fall gardening season. Stolons or runners can be an important part of reproducing within the strawberry patch. Originally when we plant these strawberries we may plant them twenty-four inches apart, and that leaves too much space in between the individual plant in the row. But we don't have to buy enough plants to plant every eight inches apart, we can depend on Page 1 of 11
the physiology or the morphology of the plant the fill in these spaces within the row plus save the home gardener money. That's done by either stolons or runners. A stolon is an aboveground, horizontal stem, and at the end of each stolon we are going to have a plant produced. The plant will begin to produce roots at that plant. You can see just the start of the roots here. And as soon as we get soil that is moist and can be penetrated by those roots, those roots will go ahead and grow into the soil and will establish, and pretty soon this stolon will dry up, and we'll have a new plant that will establish exactly as the mother plant was. So it will be a complete clone of that mother plant and we'll be able to extend our strawberry patch, fill in our blank areas, and that type of thing. Slide 4 There are three types of strawberries. The first type are the June bearers. The June bearers are the primary commercial type grown, but will also do very well in the home garden. They have a higher quality fruit than the day neutrals and the everbearing types that we'll talk about in a few minutes. Even though the fruit is produced in June, the flower buds are set the previous summer, typically in August in response to shortening day length. Flower buds that were set last August will be harvested as fruit the following June. Because the flower buds are set the previous August, you do not want plants to stress during the summer. June bearers will typically produce many runners. There are many types of June bearing cultivars, and many universities do work mostly on the June bearers. We have several varieties that we can choose from in this area that were primarily developed by Washington State University at the WSU Puyallup Research and Development center or Oregon State University. One of the older varieties still produced is Hood, an early season variety with medium to large fruit and excellent flavor. Puget Reliance, a WSU release from WSU Puyallup, is early to mid season with large to very large fruit and good flavor. Shuksan and its sister varieties Rainier and Olympus were released by Washington State University in the late 1960s. They tend to be mid season to late with very good to excellent flavor, and medium to large fruit. Totem is one of the more common processing varieties. It's mid season with medium to large fruit and very good flavor. Benton is mid to late season, medium fruit, and excellent flavor. WSU's most recent release is Puget Summer, released in 1998. It is a very late variety with production starting mid to late June, with fruit sometimes harvested as late as early August. The fruit are medium to large, but the size can fall off rapidly to small, and has excellent flavor. Two very late varieties released by Oregon State University have medium to large fruit and excellent flavor, and these varieties have done very well at WSU Puyallup. They are Independence and Firecracker. Slide 5 Everbearing varieties produce a distinct spring and fall crop. As compared to the June bearers, they produce relatively few runners. They are typically planted in the hill system, where plants are set in double or triple rows with twelve inches between plants and aisle ways that separate the double or triple row sets by one and a half to two feet. The fruit will typically be smaller than June bearers, and the overall seasonal yield will also be less than June bearers. Three common cultivars that are still available are Quinault, Fort Laramie, and Ozark Beauty. Quinault can still be found in garden stores throughout the region. The cultivar will produce low to medium yields and medium to Page 2 of 11
very soft fruit with fair flavor. Fort Laramie and Ozark Beauty are typically found in mail order catalogs and online. The yields tend to be low to medium, and the fruit tend to be small to medium with fair flavor. Day neutrals are the newest type of strawberry. They are developed in the 1960s at the University of California. They will produce a continuous crop of fruit throughout the summer and into the early fall; however, they will only flower when temperatures are below ninety degrees, so you can have gaps in production during extremely hot streaks of weather during the summer. They also produce fewer runners than the June bearers, and are also planted in the hill system. Many times nurseries or garden stores will be confusing by calling them also everbearing even though technically they are day neutral varieties. Day neutral refers to the aspect that the plants will set flower buds and flower regardless of the day length, whether it is shorter days or longer days of sunlight. The overall yield and fruit size is also less than June bearers. Some common cultivars of day neutral strawberries are Tri-star, Tribute, Albion, and Seascape. Tri-star and Tribute are the older varieties will lower yields and small to medium sized fruit, but very good to excellent flavor. Two newer varieties from the University of California are Albion and Seascape, with medium yields and larger fruit with better flavor and they tend to be firmer. They are good for commercial production and very well suited to the home garden. Slide 6 Planting strawberries. We always recommend to plant Washington State Department of Agriculture certified plants. These plants will be certified to be true to variety, and free from insects and diseases. Rooted runners from friends may be used with caution. We want to be careful of viruses that the plant may contain or root weevils and weeds that can be moved with the soil. Set plants in early spring, when the soil can be properly worked. This is going to vary from year to year, and region to region, and will also be very dependent upon soil type. In early spring, on a sandy soil, plants may be set in late March or early April. On heavier soils in a wetter spring, this may be May or even early June. Slide 7 Strawberry plants tend to be productive for three to five years. Soils prefer a well drained soil, an acid ph, and are native to sandy, low fertility soils. Strawberries require full sun, with six to eight or more hours of sun preferred. We want to be careful to eradicate all weeds prior to planting, especially the perennial weeds such as morning glory, horsetail, quack grass, and others with very invasive roots or rhizomes that will cause problems in our strawberry stand. Slide 8 We have two choices when selecting strawberry plants. Early in the season, bare root is going to be our main choice. Bare root plants are less expensive, have a very wide selection, and will be available early, typically in March and April. However, if you miss the purchasing time for bare root plants, potted plants will be available later. These start to appear in late April and are available in May and June; however, the plants will Page 3 of 11
be more expensive, there will be a much more limited selection, sometimes they will not be named by variety - only as everbearing or as June bearing, but the selection will be available during much of spring and sometimes into the summer. So if you miss the one planting season, or purchasing season for bare root, you can always purchase potted plants later. Slide 9 Planting strawberries at the correct depth is very important. We want to be careful to set the plants at the same depth that they are growing at the nursery, which is generally found as a soil mark on the crown. After planting and watering, the soil settles, exposing the crown completely will dry these plants out, and they will not establish properly. If we bury them too deep, the crown will rot and the plant will also die. We want to make sure we plant the plant at the same depth it was growing in the nursery, to be sure to water thoroughly the soil around the roots, and add additional soil or take soil away if the crown is to deep or too shallow after watering. The plant in the middle shows the proper planting depth. Slide 10 The hill system works very well for day neutral and everbearing varieties. We'll set the plants twelve to fifteen inches apart within the row and then remove all runners that are produced so we can maintain our spacing in the hill system. Mulches are a welcome addition to any small fruit production area, as this will keep down weeds, maintain moisture, and keep the soil a bit cooler. Row covers can be used, especially when night temperatures are going to be cool in mid to late spring, and raised beds can certainly help improve our soil situation in providing a productive area for strawberries. Slide 11 Plastic mulches can also be used. Commonly used in commercial production, they can reduce weeds, keep the fruit cleaner, and maintain moisture. But they do break down over a period of years and may not work as well for the home gardener. Slide 12 There are two types of strawberry planting systems. The first is the matted rows. In matted rows we set plants about twenty-four inches apart within the row, and space the rows two to three feet apart. We'll allow runners to fill in every five to eight inches with an average of six inches between plants within the row, and sweeping the runners that go between the rows back into the row so they can establish. Slide 13 Focus a little bit on our newest cultivars from Washington State University. Puget Summer was released by WSU in 1998. The fruit are large, juicy, and aromatic, although fruit size does fall off dramatically from year to year. It is a June bearer, and one disease it is very susceptible to is powdery mildew, but it does produce in the first main year of production, very large, sweet glossy fruit. Page 4 of 11
Slide 14 Another variety released by Washington State University is Puget Reliance. Large fruit with a sweet tart flavor, not aromatic like our typical June bearers, but has very good virus resistance and will maintain its productivity in the garden. Slide 15 Plants are typically produced from tissue culture. Tissue culture is used extensively for strawberry, raspberry, blackberry, and other crop propagation. This is taking a few cells off the plant and growing them in an artificial medium once the variety has been developed. Please do not confuse this with genetic modification or genetic engineering; it is micropropagation and is completely different. Many of our plants new varieties are propagated using tissue culture. Slide 16 In the garden strawberries are propagated by runners, or more technically known as stolons. Stolons are aboveground, horizontal stems. This is a form of asexual propagation where the daughter plants will be the same as the mother plant that produces them. Here you can see the small roots just beginning to form and will become rooted and the plant will become established. Slide 17 Strawberries will begin blooming in May. Here we can see a flower cluster with approximately seven flowers in the cluster. The first flower will typically be the first to develop fruit and will be the largest fruit. Slide 18 Here we can see extensive fruit set as we get closer to harvest. Slide 19 Another picture of extensive fruit set. Slide 20 An extensive fruit set with many of the fruit ripe and ready to harvest. Slide 21 And the goal of all home gardeners is to have beautiful, juicy, aromatic, large fruit. Slide 22 Fertilizers. For June bearers we fertilize and irrigate in August after production. Do not apply fertilizers in the spring to June bearers, unless the stand is very weak. This will Page 5 of 11
produce excess foliage, less fruit, softer fruit that will be more susceptible to botrytis fruit rot. On average, apply two ounces of nitrogen per each foot of row. Use a balanced fertilizer such as triple sixteen or an organic fertilizer. Everbearing strawberries and day neutrals should be fertilized with the same amount of fertilizer as June bearers, but it can be divided into four applications or three applications and applied in equal installments from spring to early August. Since the plants will be continuously producing fruit, they should have a consistent source of nutrients. Strawberries require about one to one and one half inches of water per week during the growing season. More water may be required during very hot weather, on sandy soils, or where rainfall has been scarce. We want to be sure that we wet the soil six to eight inches deep per irrigation. Most of the strawberry plant roots will be located in the top foot, so we do not have to irrigate excessively deep. There are two critical times for adequate soil moisture. From bloom through harvest, which will typically be May through July, and that's going to depend on your soil type and how hot the harvest season is. And from late August through early fall, when the plants are setting flower buds for next year s harvest. For the home garden, a soaker hose or drip irrigation is ideal, but the bottom line is we do not want to let plants stress. Slide 23 Strawberry diseases. Strawberries are affected by a number of diseases, a few of which are important to the home gardener. Botrytis fruit rot or gray mold is one of the most common. This picture shows several fruit that are infected and showing the signs of gray mold. Where fruits touch each other, the disease will rapidly spread. Overhead watering will also splash spores from one fruit to another, causing further infestation. The best thing the home gardener can do is remove infected fruit, and take it out of the garden to reduce the infestation of other fruit. Slide 24 Strawberries in the home garden are popular, but one thing that isn't very popular are moldy strawberries. And especially those seasons we get lots of rain or the home gardener overhead waters or has applied too much fertilizer and the plants are extra large with large leaves and soft fruit, and in humid weather with warm temperatures, moldy strawberries can be a huge issue. Where we really don't have fungicide anymore for the home gardener, cultural techniques are the important thing to remember for reducing the amount of moldy berries in the garden. If you look at a good example - here is a berry that is all moldy, and you can see it's completely taken over with botrytis, which is a disease that causes mold on strawberries. It's also referred to as gray mold. You can see here it was touching another strawberry. Where it has touched, that strawberry also has a presence of gray mold. Here we even have gray mold on green strawberries where it was touching this one. Even if they're not touching, we can get wind that's going to blow the spores that are very evident on that fruit, to neighboring fruit, or if it rains or you have overhead irrigation, those droplets are going to splash the spores directly from one fruit to another. One thing we do not recommend it doing is, while we do recommend harvesting the moldy fruit, but do not throw it in the center of the aisle or in the center of the walkway between the fruit. That's going to maintain a source of infection for other fruit, and you want to completely eliminate it from the garden, where it can't reinfest your strawberry fruit. Page 6 of 11
Slide 25 Common leaf spot. All of our cultivars are susceptible to the many races of common leaf spot. Common leaf spot is typically found to have a dark purple halo with a tan spot in the middle. Although our varieties will have some resistance, cool, wet spring weather will certainly increase the incidence of the disease. Typically our plants will grow out of it, and no control is recommended. Slide 26 Powdery mildew. Varieties such as Puget Summer are sensitive to powdery mildew, as are the varieties Tri-star and Tribute. Powdery mildew will appear as white powder on the underside of the leaf, and it will cause the leaves to curl upwards, much as if they've been hit with a dose of lawn spray. By turning the leaf over, you'll be able to see the white powdery signs of powdery mildew disease. Slide 27 Insects. One of the most common insects found on strawberries are root weevils. The adults feed on leaves and cause notching. The larvae feed on roots and cause the plants to wilt. Many home gardeners however say that I never see root weevils on my strawberries. It is recommended to take a flashlight and look in the garden an hour or two after sunset. In June this will typically be around 11 PM. No effective insecticides are available for the home garden, but beneficial nematodes have worked and are a possibility for the home gardener. Slide 28 The adult root weevil will feed on the leaves, causing extensive notching on the leaves. The larva, which appear as tan colored, "C" shaped larva when disturbed, will feed heavily on the roots. The adult weevils are small, an eighth of an inch long, and can be black or brown depending on the type. At least four types of weevils will attack strawberries. You can see in the picture that they can cause heavy grazing on the plants. If heavy infestations of root weevil occur in the home garden, it may be necessary to find a new space for strawberries that hopefully will have no or low root weevil populations. Slide 29 Spittlebugs are more of a nuisance on strawberries than anything else. Their unsightly spittle and messy spittle isn't appreciated by most home gardeners. Although they do feed on the plant, they don't necessarily cause much damage, and the plant can be free of spittlebugs with a good washing from a garden hose. The insect is very similar to an aphid and will typically be found in the center of the spittle mass. Slide 30 Earwigs are also more of a nuisance on strawberries. They'll get in cracks and crevasses in the fruit and will typically be found by the home gardener during harvest or Page 7 of 11
in the refrigerator after they crawl out of the fruit. No control is necessary for earwigs. Slide 31 Slugs are the bane of any home gardener. They readily feed on ripe strawberry fruit, consuming much of the fruit, or hollowing out one side of the fruit. We have to be very careful about slug control in strawberries. We want to be careful not to put slug bait, meal, or other attractants in the garden patch that attract slugs in or allow the slugs to feed on them and then feed on fruit. It is best to use other cultural methods such as boards that will attract slugs underneath so they can be sliced in half, or other methods of keeping down vegetation around the strawberries and trying to get a handle on the slug population. Slide 32 In rural areas deer can be a real problem around strawberries and many other small fruits. They will come in and graze on the leaves and rapidly graze down a field of strawberries. They'll especially be a problem in rural areas near woodlands where they can hide during the day and come out and graze in the strawberries when less activity is around. Deer fencing is a way of keeping deer out of the garden, followed by row covers. Slide 33 Birds are always a problem in strawberries. Damage can be identified by pointed notches in the fruit. Many types of birds are capable of feeding on strawberries and netting is very effective for all types of birds. Slide 34 Birds are a major problem in all small fruits. A variety of birds love strawberries, they love raspberries, they really love blueberries. Here's an example of bird damage in a strawberry where they have pecked out the side of one of the fruit. And once they get in here they'll certainly return and not consume the whole fruit, but certainly do a lot of damage to a number of fruit. It's very easy for the home gardener to deter birds, primarily through row covers or netting. By just throwing the netting over the fruit as they're developing and turning red you can certainly keep all or most all of the birds off of that crop, but it does have to be out there before the fruit ripens up or the birds will start getting in there and doing damage early. Netting is available online, through catalogs, or in many of our garden stores now in amounts that is affordable and can be easily managed by the home gardener. And if it's put on just ahead of the crop ripening and removed promptly at the end of harvest, the netting should be good for several seasons. Slide 35 Environmental problems on strawberries include frost. Strawberry flowers are very sensitive to frost and any temperature thirty degrees Fahrenheit or lower. After a frost has hit, affected strawberry flowers will have a black center. These flowers will produce Page 8 of 11
no fruit, or will produce distorted fruit. If frost is predicted, the best thing to do is take a polyethylene spun row cover and cover up the plants during the night; however, please remember that strawberries do require bees for pollination, and the row covers do have to come off during the day during bee activity. Slide 36 Catfacing, or distorted fruit, is a very common problem in the home garden. It's often times caused by nutrient deficiency, and lots of times multiple nutrient deficiencies, including boron. Catfacing can be caused by a virus infection, or it can be caused by incomplete pollination. Home gardeners are reminded that soil fertility is important, especially in our sandier soils. An organic fertilizer or an inorganic fertilizer with trace nutrients may improve the situation. Slide 37 Weeds can be a serious problem in strawberries, and the weeds are too numerous to name. Here is an example of Equisetum, or common horsetail, infesting a small patch of strawberries. Rototilling or hoeing will remove the top growth of many of the weeds, but remember, all invasive perennials will move back in after they have a chance to grow back. Eradicate weeds prior to planting, hoe or hand pull weeds as they emerge. Slide 38 Weeds are a major problem in strawberry patches. Because strawberries are shallow rooted and we have walkways between the rows of plants, they tend not to be very competitive with weeds. Here's an example of a native plant that is a weed, Equisetum or common field horsetail. You can see it coming up here between the rows, within the row, and once it becomes established it will rapidly take over a strawberry patch. Within the home garden, the easiest way to manage this weed is by hand pulling, and because this is a very very deep soil, the spreading rootstocks will go as deep as there is soil. So by pulling now we're going to keep the weeds down during the fall/winter, and later on next spring these weeds will emerge again. And that's true for many of the weeds that are common in strawberries, whether it's creeping perennials such as quack grass or Canada thistle or horsetail, or annual weeds such as barnyard grass, smartweed, and many other weeds. We are going to have to be very persistent by using plastic to keep them down, such as black plastic, mulches to keep down annual weeds, or constant hoeing, hand pulling, and cultivation to keep down the other weeds and allow the strawberries to be very competitive. Slide 39 All of Washington can have very dry summers, and drought is the leading cause of poor fruit production in the region. Ninety percent of the strawberry roots are located in the top twelve inches of soil. Irrigation is essential during the summer, both from bloom through harvest if we have an extremely dry spell during that time, and also later on during the summer during flower bud set for next year s crop. Remember, do not let the plant stress. Page 9 of 11
Slide 40 Alpine strawberries are very common in the home garden. The fruit tend to be small, but very aromatic with a nice mild strawberry flavor. Cultivars include Alpine, Baron Solemacher, and Ruegen. Berries are small and bright red, but plants are not very durable and are very susceptible to viruses. Here is a picture of a typical Alpine strawberry at one quarter to one half inch long as compared to the June bearer that may be up to two inches long, so they are very small. In terms of number of berries they will be very productive, but in terms of yield they'll be very low. Many of the fruit will fall on the ground and will readily volunteer new plants next year. Slide 41 Alpine strawberries are a popular addition to the home garden. Alpine strawberries are almost like wild strawberries, they have very small fruit as you can see, there is both the red and a yellow version that taste fairly similar. They are typically started from seed and most seed companies will sell the seeds of Alpine strawberries, and during the harvest season they will produce a ton of berries per plant. As you can see they are very small, they will reseed themselves, not all of the fruit ever get all picked and those seeds will certainly volunteer and lead to more plants. They have a different flavor than the traditional everbearing strawberry; they'll have more of an intense wild strawberry flavor and are enjoyed by all. Slide 42 Strawberries can easily be grown in containers such as barrels, planters, and hanging baskets. The gardener must pay very close attention to water and fertilizers. Because they are in a pot, they can dry out very rapidly. Day neutrals are best suited to containers. Containers and soil mixtures must permit excellent drainage, and runners should be removed during production. Containers can provide abundant yields in a small space; however, they must have adequate rooting depth, full sun, consistent moisture, proper fertility, and a good soil mixture. Although this container is rather ornamental, it has very little rooting depth from layer to layer and dries out very rapidly in full sun. This is a container I had, and in our first year of production it produced four berries, which was good considering our family had four people in it, but production could not be maintained and it was a failed experiment. Slide 43 Regardless of the type of container, ensure that the mother plant has an adequate rooting depth. If desired, runners can be rooted in four inch pots for more production, but most of the runners should be removed to maintain a strong, healthy mother plant. A minimum rooting depth of about fifteen inches is important. This will allow for some moisture reserves and adequate rooting depth for water and moisture reserves. Slide 44 Strawberry towers can be an interesting project for small spaces. This allows for watering from the top and can be very productive. Page 10 of 11
Slide 45 Strawberry containers are ornamental as well as functional, but remember to watch out for moisture stress. Slide 46 Although hanging baskets looks very productive hanging in greenhouses or in magazine ads, fruit production is generally disappointing. They take a lot of work and although you can get some production, overall fruit production will be fairly small. Slide 47 Ornamental strawberries are also very popular. Frageria and Potentilla crosses have resulted in varieties such as Lipstick and Pink Panda. Most have a very nice ornamental pink flower, can handle some shade, will produce fairly small berries, and can spread rapidly to form a nice groundcover. Slide 48 Strawberries - the end. Page 11 of 11