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Plugs, Bare-roots, Cut-offs, and Frigo Transplants
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Transplant Types - Strawberry transplants are available in many different forms. Proper planting is critical for all transplant types! Plugs - A.K.A. tray plants, potted plants, rooted plants, or containerized plants. This plant type is generally the most expensive, but offers several advantages over bare-root transplants. In cooler climates plugs can be planted earlier than green-top bare-root plants (not available until mid to late September). Plugs require minimal irrigation after planting compared to green-top bare-roots, and plugs can be mechanically transplanted. In general, plugs are easier to manage because they can be held in transplant trays until planting. Green-top Bare-roots - This is the most common type of transplant. Most of these plants are supplied by nurseries in North Carolina or Canada. These plants are generally the most tender and do not handle stress or long storage. These plants should be planted as soon as possible after nursery digging. Cut-offs - A.K.A. California trimmed plants. These are generally the least expensive transplant type. These plants tend to establish slower and thus have only been successful in the Eastern part of the state (warm winters provide more time for growth). Even in the Eastern part of the state, cold fall/winters could result in poor production from this transplant type. In general, these plants produce a small canopy that may be advantageous for reducing disease. These plants have also tended to produce fewer but larger fruit. Frigo plants - A.K.A. cold stored plants are dormant transplants that are dug in late fall / early spring and cold-stored for planting in the late spring / early summer. This plant type is an option for cooler climates that need plants early but do not want the additional expense of plug plants. Planting Date - Planting date will vary depending on location and environmental conditions. Planting date affects crown development and flower initiation. In general, Sweet Charlie should be planted 1 week earlier than Chandler. Camarosa should be set a few days before Chandler. Also, it is wise to plant the heavy red clay ground 5 days earlier than the more loamy "gray soil". Plant Density - Locations similar to North Carolina's Coastal Plain should plant Chandler or Camarosa at 14" in-row spacing (due to the milder winter climate resulting in more vegetative growth). Growers located in the central piedmont region should plant these varieties at 12" in-row spacing due to productivity losses associated with a 14 inch spacing (approximately 15 % yield reduction). Thus, if setting plants on a 5' bed center, 17,500 plants/A would be needed for a double-row bed. The double-rows should be spaced 14 apart on the 30 " wide bed top. The plants are staggered - not set on the square. Sweet Charlie can be planted at a 2 inch closer in row spacing (12 inches coastal plain, 10 inches piedmont). Plant Quality - Whether the transplant source is bare-root or plug, plant quality is one of the most important factors in strawberry production. Healthy, actively growing transplants are needed to ensure fall flower initiation. Once bare-root transplants are received by the grower they should be immediately planted or kept in cold storage. Bare-root transplants can be planted more easily with a transplant tool. The tool is usually made by bending a piece of 2 inch wide steel at a 90 degree angle such that there is a 4 inch handle and an 8 inch shaft. The base of the shaft is cut to aid in punching. |
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Bare-root or Plug
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The majority of strawberry transplants are currently produced by digging daughter plants from the nursery field, removing soil from the roots, cold storing the plants, and then planting the bare-root plants in a field for fruiting. These plants can be stressed during this process. Additionally, inconsistency in strawberry transplant production and handling, coupled with post transplant conditions can contribute to delayed flowering and subsequent fruiting irregularity. One of the most serious problems with bare-root transplants is transplant quality. Low quality transplants can result in uneven or poor stands, as well as disease and spider mite epidemics due to pathogen infestation and plant stress. The percentage of marketable fruit is therefore reduced. Mechanical digging and shaking (to remove soil from roots) often damages roots and breaks petioles, reducing the number of functional leaves for use by the transplant during establishment and creating possible sites for pathogen infection. Bare-root transplants often require large quantities of water at planting, especially in warm climates. This further exacerbates plant pest problems and leaches nutrients. There have been years when nurseries have had difficulty digging plants because of adverse weather conditions during the digging period. Weather conditions also affect the amount of chilling a plant attains. Varying weather conditions during the transplant production season can cause variability in transplant performance from year to year. The above problems of transplant variability can be avoided by the use of plug transplants. Plug (tray) transplants have been used successfully in Europe since the late 1980's (Hennion et al., 1996) and have been researched across North America. In North Carolina, plugs have been reported to have several distinct advantages over bare-root transplants: plugs required only 10% of the water needed for bare-root establishment in spring production systems, a mechanical multiple-row plug transplanter could be used for planting, minimal root damage during transplanting which provided for quick root establishment, and plant survival was greater (Poling and Parker, 1990). |
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Soil Preparation |
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Subsoiling - Subsoiling is needed every few years on heavy soils. This needs to be done N-S, and E-W (both directions). Subsoiling needs to be done DEEPLY to loosen the soil and break up the plow layer (at 10-12 inches). Breaking up this layer will require setting the draft control so that the V-ripper doesn't come up easily when it hits the hard spots. This operation requires extra hp! Be sure to incorporate your lime (use dolomitic which supplies Mg) when you subsoil. Soil pH should be 6.0. Disking - The goal of disking is to get the soil as "fluffy" as practically possible (breaking up clods, etc). One grower describes this step as "getting the soil like a bed of pillows". You don't want to use equipment that will compact the soil (a rotary hoe or rototiller). This is the best time to incorporate your N,P and K fertilizers (see the fertilization and irrigation section). Work these to a depth of about 6 inches. Soil Moisture - Having the proper soil moisture is of critical importance for bed-making and fumigation operations. Growers must often set up irrigation pipe and irrigate at least 1/2 inch a few days before fumigation. If you own your own fumigation rig, you have the luxury of waiting for a nice soaking rain (for the period from say Sept 10 through Sept 18). Methyl bromide fumigation should be done at least 10 days prior to transplanting (most alternatives to methyl bromide require longer waiting periods and proper soil moisture is even more critical). Bed Making - Some of our low organic matter, red clay soils are aptly described as "dinnertime soils" - they can be too wet to fumigate before lunch, and too dry after lunch to make a good bed where the shoulders begin to crack and come apart. A real good idea is to disk the soil just ahead of fumigation. Some growers will lightly disk an acre, and then fumigate it immediately. If you disk all of your plasticulture acreage early on a hot sunny day, chances are that it will be too dry for fumigation and bed-making. Leave that moisture trapped beneath the soil's upper crust until you need it. An excellent strawberry bed has the plastic mulch in direct contact with the soil beneath - you get this by going to these extra pains. If there are air pockets beneath the plastic, plant growth will be slow in fall and winter (heat from the black plastic will not be conducted into to the soil if there are air pockets - in fact, the black plastic can have a cooling effect if it is not in good contact with the soil beneath). Fumigation - The advantage of owning your own fumigation rig is that you can schedule fumigation when the land is ready (which is not necessarily when the custom fumigator is ready to come to your farm). The real difficulty with red clay is getting this type of soil properly conditioned for good fumigation and bed-making. Compaction and clods are the net result of working the land when too wet. Click here to return to the Proceedings page. |