Starting Vegetable Transplants under lights

Starting and growing transplants under lights
Curtis Swift, Swift Horticultural Enterprises, LLC

Introduction:

Transplanting is the process of shifting of plants from one place or growing medium to another. If done properly plant stress will be minimized and the production of flowers, fruits, and foliage can be enhanced.

Starting your own transplants (seedlings) indoors under lights or in a greenhouse where adequate light is available avoids problems with direct seeding into garden soil where seedlings often have to battle their way through soil crusts. Starting your own transplants can result in higher quality plants and cultivars that are not available at local greenhouses or garden centers

Starting plants indoors under lights the seeds germinate under ideal conditions. Starting them at the proper time can extend the growing season and create earlier harvest when compared with direct seeding in the field. Transplants you grow are typically not exposed to the myriad of virus, fungal or insect problems commercially-grown transplants may be exposed to.  While it is often difficult to pinpoint when a transplant was exposed to a problem, the timing of symptom development often leads one to suspect the origin of the infection was the commercial greenhouse. Your goal is to produce vigorous and healthy plants ready to be planted in the garden when conditions are appropriate.

Not all vegetables are worth the effort to start as transplants. Even though you can grow them from seed in the home or greenhouse, it is difficult to successfully transplant these to the garden. These include carrots and beets, leafy biennial herbs (dill), heading types of Chinese cabbage, and cucurbits (cucumbers, pumpkins, squash); they don’t like their root systems disturbed.

Radish, leaf lettuce, and spinach develop so quickly when seeded in the garden starting them as transplants is not worth the effort. Radishes are often ready to eat in fourteen days from the time of seeding.

Vegetables such as tomatoes, peppers, eggplant, okra, head lettuce, and broccoli are typically started as transplants and that is where I would suggest you focus your efforts. Sweet potato grown from rooted cuttings is another vegetable that would benefit from being started in the home.

Age affects transplant quality:
 

Smaller, stocky plants that have not started to bloom and/or set fruit adapt to the garden more easily than leggy transplants or plants with small fruits. Tomato plants four to five weeks old grow and produce a higher yield than older transplants. The younger transplants often develop healthy root systems which helps avoid problems with the splitting of the fruit and blossom-end rot common when older transplants are used.  Using younger plants does not guarantee these problems will be eliminated but helps control these problems. The ideal plant is short and stocky, which for many transplants will be about six inches tall and six inches wide. The table at the end of this article provides the recommended age for vegetable transplants when planted into your garden. Since transplants are more susceptible to cold than plants direct-seeded to the garden, transplants are usually planted after the average last spring freeze unless some form of frost protection is provided. If you know that date, count back the number of weeks indicated on the table, add the number of days needed for germination, and plant the seed accordingly.

 

Problems you need to avoid:
 

Low light, excessive levels of nitrogen, and high temperatures during transplant development causes excessive stem elongated.  Such stems are more susceptible to diseases and breakage. In most cases the diseases that attach young seedlings are the result of using soils (planting media) that have not been properly pasteurized.  If you insist on mixing your own planting media for seedlings, it should be placed in the oven and cooked to eliminate all the water-molds and other plant pathogenic organisms that live in that soil. Pasteurization occurs when the soil is moist allowing heat to reach every bit of soil. Forty-five minutes in a two-hundred degree oven usually does the trick. If you have a temperature probe insert that into the center of the soil mass and when the temperature reads one-hundred and eighty degrees for thirty minutes the soil has been properly pasteurized.  Exceeding that temperature for longer than thirty minutes is not recommended.

 

Damping-off is caused by fungi or fungal-like organisms which attack the base of the stem next to the planting medium. Non-pasteurized planting medium, the use of dirty flats, trays, or pots, and dirty tools are often the cause. Fungus gnats can also carry some of these plant pathogens from contaminated house plants to your seedlings.

The best planting medium for starting seedlings are the soil-less mixes.  They are usually free of pests, have good water-holding capacity, are well aerated and drain properly, and are low in salts.  Some even have fertilizers added to help keep your young seedlings perking along in a healthy condition.  This doesn’t mean however, you don’t have to fertilize.

 Transplants can be started in individual pots, cubes or open flats. When started in open flats, the young seedlings will need to be pricked out (transplanted) and repotted in individual pots when the seedlings have their first true leaves. Some gardeners will do this by pulling the tiny plant out of the flat of planting media by their seed leaves. This is a fast and easy way to do transplant a large number of seedlings but can be damaging to the plant. Some gardeners remove the tiny seedlings with sharpened Popsicle stick.  

 Lights:

 Plants grown without sufficient light are yellow or lighter green than they should be.  These plants are said to be chlorotic. They stretch for the light, have thin stems, and in general are not as healthy as plants grown with adequate light. Gardeners who depend on natural light for the proper development of their seedlings cannot produce quality transplants.

The light used by plants comes in different frequencies and the packets of energy carried by the different frequencies energize different responses in the plant. Exposure to red light increases seed germination while far-red light increases legginess. Since regular incandescent bulbs produce more far-red light than fluorescent lights, the latter are preferred for seedlings.  To ensure adequate light reaches all parts of the seedling, fluorescent lights should be placed no more than four inches above the top of the plant. The plants need to be spaced far enough apart so shade is not a problem. Full spectrum grow lights are recommended if you have fixtures with only one tube but if you have a two-tube fixture one cool-white and one warm-white tube provides the same spectrum of light.

If you decide to use incandescent lights for your seedlings, they need to be placed between one foot and three feet from the top of the plants even then you might burn your seedlings unless you use bulbs specifically designed for plants. The Spot Grow type incandescent bulbs are said to provide the proper plant growth enhancing light characteristics. Plastic sheeting is available designed to reduce the amount of far-red light and is an option for those growing transplants with incandescent bulbs.

Temperature:

Plants placed on the window sill, while not providing adequate light, also are subjected to large temperature fluctuations between day and night and sunny and cloudy days. Temperatures cooler than optimum often increase disease problems and can cause the development of rough fruit in tomatoes and bolting (i.e. development of a seed stalk) in onions and other biennial vegetables. Warmer than optimum temperatures can cause weak and spindly seedlings.

Fertilizing your transplants:

Nitrogen (N) is what your seedlings require to develop into healthy transplants and different types of vegetable seedlings require different rates and frequencies of applying nitrogen. Tomato seedlings need to watered with fifty to one-hundred parts per million (ppm) of N or once a week with water supplemented with two hundred and fifty to three hundred ppm of N. Peppers prefer a daily watering containing one-hundred ppm of N, while cole crops (cabbage, broccoli, cauliflower, etc.) prefer one-hundred to one-hundred and fifty ppm of N per week. The vine crops (squash, pumpkin, etc.) need two to four applications of one-hundred to one-hundred and fifty ppm of N per week.

Ok, now that the amount of N these transplants require has been provided, how do you mix up a solution containing one-hundred ppm of N?

When you purchase a granular or liquid fertilizer at a garden center it will most like give the percentage of N along with the percentage of phosphorus (P), potassium (K) and other nutrients.  The container may also give the parts per million but this is seldom the case. The percentage of N in the product is easy to convert to ppm as follows:

10% = 100,000 ppm
12% = 120,000 ppm
15% = 150,000 ppm
20% = 200,000 ppm
and so forth.

Now that you know the ppm of N in the product you purchased, you need to dilute with water to obtain the ppm of N needed by your seedlings. This is quite easy to do with a liquid fertilizer as you are adding a liquid (the fertilizer) to a liquid (the water). With a granular product you have to turn the fertilizer into a liquid.  This is done by adding it to water. Measure out a measured amount of water and add sufficient dry fertilizer to double the level of the water in the container.  This will reduce the percentage of the fertilizer by half; a 20% N dry fertilizer will then contain 10% N.

You will need a pipette, eye dropper, or small measuring cup like those that come with cough syrup to dilute the fertilizer product to what is needed by your seedlings. These are usually marked in milliliters and that is what you need.

The formula you need to use is C_i x V_i = C_f x V_f where

C = ppm
V = volume in milliliters
i = initial
f = final

If you have a product that contains 12% N (120,000 ppm) and need a final solution of 100 ppm of N, plug 120,000 into the formula at C_i. Let’s make one gallon of this mix. One gallon is 3,800 ml so the formula C_i x V_i = C_f x V_f will look like this:

120,000 ppm x Vi = 100 ppm x 3,800 ml. When you do the computations you receive the number of milliliters (3.2) that need to be added to one gallon of water to create a N solution of 100 ppm.

If you want to make less than a gallon, plug the following into V_f:

1 quart = 950 ml
1 pint = 475 ml
1 cup = 240 ml

To make one gallon of a 100 ppm N fertilizer solution it will take:

3.8 ml of a 10% N fertilizer product
3.2 ml of a 12% N fertilizer product
2.5 ml of a 15% N fertilizer product
1.9 ml of a 20% N fertilizer product

Hopefully this article helps you grow healthy vegetable transplants.

 

Table 1

Vegetable	Soil Temperature for seed Germination 1			Time Required for growing Plants for Field Transplanting 4
	Optimum Range (oF)	Day 2 (oF)	Night (oF)	Time (weeks)
Asparagus	60 - 85	70 - 80	65 - 70	8 - 10
Broccoli	68 - 86	60 - 70	50 - 60	5 - 7
Brussel Sprouts	75	60 - 70	50 - 60	5 - 7
Cabbage	45 - 95	60 - 70	50 - 60	5 - 7
Cauliflower	45 - 85	60 - 70	50 - 60	5 - 7
Celery	60 - 70	65 - 75	60 - 65	10 - 12
Corn, Sweet	60 - 95	70 - 75	60 - 65	3 - 4
Cucumber	60 - 95	70 - 75	60 - 65	3 - 4
Eggplant	75 - 90	70 - 80	65 - 70	6 - 8
Lettuce	40 - 80	55 - 65	50 - 55	5 - 7
Muskmelon	75 - 95	70 - 75	60 - 65	3 - 4
Okra	85 - 95 3	70 - 75	65 - 70	4 - 6
Onion	50 - 95	60 - 65	55 - 60	10 - 12
Pepper	65 - 95	65 - 75	60 - 65	6 - 8
Squash / Pumpkin	70 - 95	70 - 75	60 - 65	3 - 4
Tomato	60 - 85	65 - 75	60 - 65	5 - 7
Watermelon	70 - 95	70 - 80	65 - 70	3 - 4

 

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1. Adjust temperatures slightly to alter growth rates.
2. Select the lower temperature on cloudy days. Daily fluctuations to 60^o F. or lower at night is essential for some vegetables.
3. A hard seed coat prevents good germination. Treatment of seeds with concentrated sulfuric acid for 2-3 hours or soaking seeds in hot water (113 ^o F) for 1 1/2 hours improves germination.
4. Transplants older than recommended suffer more shock when transplanted to the garden and often produce less of a crop over the course of the growing season than transplants of the proper size and age.

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References used:

Lorenz, O.A., and D.N. Maynard. 1988. Knott's Handbook for Vegetable Growers, Third Edition. Wiley-Interscience Publications
Splittstoesser, W.E. 1984. Vegetable Growing Handbook, Second Edition. AVI Publishing Company, Inc.
Yamaguchi, M. 1983. World Vegetables; Principles, Production and Nutritive Values. Van Nostrand Reinhold Company.

 

Pesticide Applicator Training Workshop December 14, 2012

Pesticide Applicator Training Workshop
December 14, 2012

Country Inn, 718 Horizon Drive, Grand Junction, CO 81506

Speakers – Curtis Swift, Ph.D. (QS # 00019) and Jude Sirota (QS # 00759)

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For more info Call Dr. Swift  970.778.7866

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Why you should Attend?

Private Pesticide Applicators who apply restricted use pesticides are required to be certified by the Colorado Department of Agriculture. Continuing Education Credits are required to maintain this certification.
Commercial Pesticide Applicators, i.e those who apply pesticides for hire, are required to be certified by the Colorado Department of Agriculture and receive the required Continuing Education Credits to maintain that certification.
The morning sessions are required for Private Pesticide Applicators to maintain their certification.
Commerical Pesticide Applicators also require the morning sessions. The afternoon sessions are for specific categories.
The paperwork necessary to certify attendance at these sessions will be forwarded to the Colorado Department of Agriculture upon completion of the training. Attendees will receive a copy of the attendance verification form for their records.

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Registration is Easy! The registration form is at the end of the program.

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The Schedule:

8:15  – 9:15 a.m. Laws and Regulations

Laws and Regulations – ½ hr; Dr. Swift –Requirements and Forms for Commercial, Limited Commercial, or Public Applicator Licensing. Each item will be discussed and samples of documents provided.
Laws and Regulations – ½ hr; Jude Sirota – EPA pesticide registration: cancellations and reregistration status.

9:15 - 9:45 Applicator Safety – ½ hr; Curtis Swift – Use and maintenance of personal protective clothing and safety equipment. Material Safety Data Sheets and label requirements.
9:45 – 10:15 Pesticides and Their Families – ½ hr; Jude Sirota – Insecticide families and their mode of action. Mode-of-action-based management to prevent insecticide resistance.
10:15 – 10:30 Break
10:30 – 11:00 Environmental Protection – ½ hr; Jude Sirota – Dust storms and Hurricanes: How weather affects pesticide applications.
11:00 – 11:30 Public Safety - ½ hr; Curtis Swift - Safe methods of handling pesticides during transportation, storage, mixing and loading, application, and cleanup equipment that must be available.
11:30 – 12:00 Use of Pesticides – ½ hr; Jude Sirota – Choosing pesticide application techniques based on label requirements.

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12:00 - 12:45 Lunch - provided for those paying for full day.

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Pest Management: Breakout room #1 – Curtis Swift

 12:45 – 1:45 Turf Pests 206 – Diseases of cool-season grasses - 1 hr 

Identification and control strategies to include cultural and chemical management.
1:45 – 2:45 Turf Pest 206 – Weed control in cool-season grasses and ornamental plants - 1 hr - Differentiating between broadleaf and grassy weeds and their control; specific info will be provided on treating weeds in ornamental beds.

2:45 – 3:00 – Break

3:00 – 4:00 Ornamentals 207 - Pests of Woody Plants - Aphids, Mites, Scales, Gallmakers - 1 hr - Identification strategies and control options to include cultural.
4:00 – 5:00 Ornamentals 207 Pests of Woody Plants -Defoliators, borers and bark beetles - 1 hr - Identification strategies and control methods to include cultural.

 

Pest Management: Breakout room #2 – Jude Sirota 

12:45 – 1:45 Agricultural Insect Control 101 – New pests on our doorstep: what growers can do to prevent the introduction and spread of exotic agricultural insect pests.

 1:45 – 2:45 Agricultural Weed Control 103 – Managing weeds so they don’t control you: developing a system of crop production that is less susceptible to weed invasions.

2:45 – 3:00 – Break

3:00 – 4:00 Rangeland Pest Control (107) / Industrial Right-of-way Weed Control (109) – one credit for one or the other will be awarded for attending this session.  Managing noxious weeds while protecting endangered/ threatened native plants.
 

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To register, complete the following and return it along with a check or purchase order to:

Swift Horticultural Enterprises LLC
450 Hill Avenue
Grand Junction, CO 81501

Your contact information: Name ___________________________________
Physical Address _______________________________________________________ email__________________________________

	Number attending	Subtotal $	Please provide names of attendees for each category
Full Day - $150 per person
Afternoon sessions - $100 per person
Morning sessions - $75 per person
Totals

Contact Info: Curtis.Swift@alumni.colostate.edu; 970.778.7866

 

 

The importance of soil testing

 

Swift Horticultural Enterprises, LLC
Swift Horticultural Consulting

High Altitude Lavender

Curtis Swift, Ph.D.

450 Hill Avenue, Grand Junction, CO 81501

970.778.7866

Curtis.Swift@alumni.colostate.edu

 

The importance of soil testing;

How to collect a sample, where to send it for analysis, and how to obtain a quality recommendation

 

Why is soil testing important?

·         To determine if the soil is appropriate for the trees, shrubs, flowers, herbs, lawn grasses, etc. you want to plant; not all soils can support healthy plant growth.

·         To learn what is needed to improve the health of those plants and reduce plant stress and reduce the potential for insect and disease problems.

·         To know what is needed to increase plant vigor, fruit, and flower production. 

A soil test provides the following:

·         What nutrients are deficient, the organic matter content, the pH and the soluble salt content.

·         What you need to add to the soil to correct deficiencies.

 You need the answers to the following items to realize the full potential of a soil test: 

·         Is this soil compatible with the plants you want to grow?

·         What nutrients are needed and when should they be applied and at what rate?

·         What nutrients should you avoid to prevent imbalances, excessive growth, root damage, etc.?

·         Are your plant problems the result of an improper fertilization program?

·         What nutrients are excessive and how can you avoid contributing to the problem?

·         Do you have a soluble salt problem and if so how can you correct it?

·         If the organic matter level of the soil is low how can you correct it without damaging established plants?  If this is a new planting what should you use and how much to improve the soil.

·         Is there a sodium problem and if so how do you correct it?

·         How can you enhance the growth and quality of the plants in this soil?

 

Recommendations: 

My job is to provide you the answers to the above questions.  My written recommendations will be specific to the plants you are growing or plan to grow in that soil. If you prefer the use of organic products in lieu of synthetic fertilizers I will provide you specifics on what products to use and how much of each is required for your plants and when they should be applied. 

Collecting a soil sample is simple. 

Shovel or trowel: Dig a hole in the area eight inches deep. Take a slice of soil off the side of the hole and throw it in a clean bucket, cardboard box, etc.  

Soil Auger or Probe: Twist/push the auger/probe into the soil to a depth of eight inches. Put the soil you collect in a clean pail, bag, or box.  

For more information on collecting a soil sample go to http://www.wardlab.com/SamplingInfo/ProperSampling.aspx#Soil.  Use clean tools to take samples.

 The soil testing laboratory needs about one pint of soil.  If the soil being tested is similar throughout the field or lawn take multiple samples from the area and mix them together for a composite sample.  If the soil appears or feels different in different parts of the field you should submit a separate sample for each soil type. If testing the soil around a tree, collect samples from the area half way between the trunk and the furthest reach of the branches and all the way around the circumference of the tree. 

 Air-dry the soil before sending it to the lab for analysis. Do NOT dry the sample on a newspaper or other surface where compounds can leach from the surface into the soil.  I use a plastic shoe box to dry the samples I mail to the lab. After the sample is dry, package it up in a plastic zip-lock bag. Keep the sample out of the sun after you have sealed the sample in the bag.

 

Where should you send your soil samples?

 I work with Ward Laboratories, Inc. in Kearney Nebraska (http://www.WardLab.com).  Their analytical fees are reasonable and they are quick and accurate. Their S-4 Routine analysis provides the information I need to provide quality recommendations.   Use the sample submittal sheet at http://www.wardlab.com/images/SampleForms/SoilSampleInformationSheetWithoutRecommendations.pdf .  Make a note on the form to have them email the results to Curtis.Swift@alumni.colostate.edu.  Make sure your name, address, and email address is on the form. Please send me an email to let me know you have sent a sample to the lab so I will expect it.

 Mail the dried sample(s), sample sheet, and payment of $19.25 per sample to:

 Ward Laboratories, Inc.

4007 Cherry Ave., P.O. Box 788

Kearney, Nebraska 68848-0788 

When I receive the results from Ward Lab I will contact you to obtain further information to make my recommendations fit your situation correctly.  

 My Fee: 

My fee for providing recommendations and associated literature based on the soil test results is $30 per sample.  

If you live in the Grand Junction area and want me to pick up the sample(s) at your home or office, mail them to the lab, and provide you recommendations, my fee is $40 per sample.  Please contact me at 970.778.7866 if you prefer this option.     

Alfalfa Mosaic Virus and Lavender

Alfalfa Mosaic Virus (AMV) and Lavender
Curtis Swift, Ph.D.

 



Image 1: Symptoms of AMV on Lavender



Image 2: Distorted yellow spotted leaves are smptomatic of AMV. Yellow spots on flower stalks are less common.

 

Introduction:

 

The Alfalfa Mosaic Virus is found through out the world and no lavender field is free of possible infection. While this disease is easily spread by cuttings they are seldom tested to ensure they are free of virus.  This does not, however, mean infection will result in a loss of yield or plant vigor. Identifying infected plants is often difficult as symptoms of infection may persist or disappear soon after infection. (Hartman, et al.)

 

 AMV was first described in California in 1931 as a mosaic virus of alfalfa. Since viruses are named for the first plant in which they are identified, the virus was named Alfalfa Mosic Virus (Hall).  AMV is a pathogen of several vegetable crops causing up to 65% yield loss of peppers (Pernezny, et al.) while the strain that infects beans is reported to be of no economic importance whatsoever. Other crops reported to be susceptible to AMV include peas (Hagedorn, 1984), soybeans (Harman, et al. 1999), celery, celeriac, and other umbelliferous crops (Davis & Raid, 2002), head lettuce (Davis, et al., 1997), eggplant, and other dicots, many of which are weeds.   This virus has one of the largest host ranges of any virus known to infect 600 plant species in 50 genera.  Daughtrey et al. indicate AMV has been reported in greenhouse flower crops to include primrose, geraniums and hydrangea.  They suggest this virus may be more widespread in flowers than reports would indicated.

 

Stunted lavender plants (Lavandula angustifolia and L. x intermedia)  with yellow spots and distorted plant growth were reported in western Colorado lavender fields in 2011.  In 2012, samples of tissue was collected from plants exhibiting yellow spotting and stunting from three widely distributed lavender fields in western Colorado and tested for virus.  Suspect tissue was collected from 'Fat Spike', 'Royal Velvet' and the lavendin 'Grosso'. A total of five samples collected from different plants were sent by priority mail to AgDia, Elkhart, Indiana for testing.

 

The presence of virus is typically determined by the ELISA procedure. For many crops, tissue from the suspect plant is macerated in a buffer solution and paper strips containing antibodies to the suspect virus inserted into the mix of buffer solution and plant tissue. This technique gives us an answer as to which virus or viruses is/are present in the sample in about five minutes. 

 

Due to the essential oil of lavender tissue, a technique called PCR had to be used to characterize (identify) the virus to family.  Polymerase chain reaction (PCR) is a scientific technique that increases a single or a few copies of a piece of DNA, generating thousands to millions of copies of a particular DNA sequence.  This technique revealed all five samples were in the Bromoviridae family of virus.   

 

This family includes:

•   Genus Alfamovirus; type species: Alfalfa mosaic virus

•   Genus Anulavirus; type species: Pelargonium zonate spot virus

•   Genus Bromovirus; type species: Brome mosaic virus

•   Genus Cucumovirus; type species: Cucumber mosaic virus

•   and others, hence the reason to have this virus characterized to Genus.

The DNA samples were found to be 97%-99% related to Alfalfa Mosaic Virus. The strain of the virus was not identified in this process.  Many strains of AMV cause necrotic local lesions, while other strains can result in yield loss, reduce winter survival, and an increase in infection by other pathogens.  No data is available on the overall effect of AMV on lavender thus further research on this problem as it relates to lavender winter survival and yield is needed.

 

Disease Management

Myzus persicae, the green peach aphid, is the most efficient aphid vector of at least 15 different aphid species that spread this virus. Aphids can acquire the virus after only a few minutes of feeding on a virus-infected plant and can immediately transfer the virus to another plant.  The virus is picked up on the outside of the stylet (needle-like mouth parts). When the aphid feeds on the next plant some of the virus particles remain in the probed plant tissue causing the disease.  This type of virus transfer is referred to as non-persistent or stylet-borne transmission, as compared to viruses that are sucked into the insect’s gut prior to being trasmitted to the next plant.  The latter is referred to as `circulator/ persistent`, or `propagative` transfer depending on whether the virus passes directly through the insect gut system, or multiplies inside the insect prior to being passed on to the next plant.  

Like the virus, M. persicae is found world wide. This aphid is a common pest of peach, cherry, and other Prunus species and insecticide treatment of those trees to prevent spread of this aphid to nearby lavender field is strongly recommended. In cold climates this insect often overwinters in warm greenhouses. 

Alfalfa Mosaic Virus can be spread through transmission of sap thus disinfecting equipment used for pruning, shaping, and other operations is recommended to prevent the spread of this virus, especially when AMV-infected lavender plants or weeds or other crokps are in or near the field.  A solution of 10% bleach solution (sodium hypochlorate) created by mixing one part bleach with nine parts water, or a spray of alcohol, or other disinfectant is recommended to treat sickles, shears, and other cutting implements between plants to help prevent spread. Bleach is corrosive so frequent replacement of cutting implements will be need if used as the disinfectant.

 

Image 3: Pigweed with symptoms of AMV.

 

All AMV-infected plants are dicots and many are weeds. Controlling weeds around the production field is key to preventing the introduction of this disease into the lavender field. It is critical that weeds be treated with an insecticide prior to being eliminated.  Hoeing, mowing, or spraying weeds with a herbicide prior to treating for aphids results in the aphids moving to other plants, some of which could  be lavender plants. Applying an insecticide to weeds prior to control can be done with synthetic products or organic approved materials such as SucraShield™, neem oil, insecticidal soap, etc.

When neighboring fields of alfalfa and other aphid-infested crops are harvested, aphids move to find other plants to feed on.  Leaving a buffer of plants between the harvested crop and the lavender field will help keep aphids from moving to the lavender. This buffer could be treated with an insecticide.  If the neighboring buffer is not a viable option the use of a trap crop around the lavender field should be considered. This trap crop could consists of several rows of alfalfa treated with a fast-acting contact organic or synthetic insecticide.  The concept is simple.  Aphids moving into the area would hopefully alight and feed on the trap crop and would be killed before they have an opportunity to move into the lavender field. Organic products typically have no residual or have a shorter residual effect than synthetic products and thus would need to be applied more frequently to maintain control of the aphids feeding in the trap crop.

Insecticides applied to lavender plants are not effective in preventing AMV infection since the non-persistent transmission of the virus occurs too rapidly.

The use of a spun-bonded polyester insect barrier over the plants helps prevent virus infections. Drought and drying winds cause aphids to move from droughty crops and dry desert areas to other crops including lavender. During such times additional steps may be necessary to prevent AMV infection of lavender.

Dodder, a parasitic seed plant, can spread this virus from infected to non-infected plants thus keeping the field field of dodder is critical.  

Image 4: Dodder wrapped around bindweed

The tolerance level of lavender to this virus is not known.  AMV infection appear to have no effect on plant growth or yield in some fields. Some growers remove infected plants while others leave them be.  More research on this aspect of the disease needs to be conducted to determine its effect on lavender in general and cultivars specifically. 

 Creating virus-free transplants and cuttings

Greenhouses used to propagate lavender should be kept free of aphids to help ensure transplants are not infected when moved to the production field or retailer outlets. The use of insect screening installed over doors, intake vents, fan housings, and other openings should be considered.  Mother plants used for cuttings should be examined for visible symptoms of the virus and not used for that purpose if symptoms are noted.  Mother plants should be kept covered with an insect barrier spun-bonded fabric if not kept in an aphid-free glass house. Having mother plants tested for AMV would be ideal but costly. 

Cuttings taken from plants infected by viruses, phytoplasma, fungi, or fungal-like organisms are often cured of their pathogens by being placed in hot water for a certain number of a minutes. Azalea cuttings infected by Rhizoctonia can be cleared of this pathogen by placing the cuttings in 122^o F water for 20 minutes without damaging the plant tissue. Virus-infected daffodil bulbs placed in 129^o F. water for an hour are made virus-free. While hot water treatment will most likely inactivate virus in lavender cuttings information on the proper temperature or length of time necessary to achieve this virus-free status needs to be determined. 

Hot water treatments are also used to inactivate virus in seed.  When seed is colllected from lavender in the process of selecting new cultivars one should consider treating the seed with hot water therapy as AMV is seed transmitted. A hot water bath of 144^o F for 10 minutes is a common treatment regimen for seed.

 

References: 

·        Chaube, H.S. and Singh, U.S. 1991. Plant disease management: Principles and practices. CRC Press, Boca Raton, FL.

·        Davis, R.M., and Raid, R.N. 2002. Compendium of umbelliferous crop diseases. American Phytopathological Society, St. Paul, MN.

·        Davis, R.M., Subbarao, K.V., Raid, R.N., and Kurtz, E.A. 1997. Compendium of lettuce diseases. American Phytopathological Society, St. Paul, MN.

·        Daughtrey, M.L., Wick, R.L., and Peterson, J.L. 2006. Compendium of flowering potted plant diseases. American Phytopathological Society, St. Paul, MN.

·        Hadidi, A, Khetarpal, R.K., and Koganezawa, H., eds. 1998. Plant virus disease control. American Phytopathological Society, St. Paul, MN.

·        Hagedorn, D.J., ed. 1984. Compendum of pea diseases. American Phytopathological Society, St. Paul, MN.

·        Hartman, G.L., Sinclair, J.B., and Rupe, J.C. 1999. Compendium of soybean diseases: 4th edition. American Phytopathological Society, St. Paul, MN.

·        Hall, R. 1991. Compendium of bean diseases. American Phytopathological Society, St. Paul, MN.

·        Pernezny, K. Roberts, P.D., Murphy, J.F., and Goldbert, N.P. Compendium of pepper diseases. 2003. American Phytopathological Society, St. Paul, MN.

·        Sherf, A.F., and Macnab, A.A. 1986. Vegetable diseases and their control. John Wiley & Sons, Inc, New York, NY

·        Sutic, D.D., R.E. Ford, and M.T. Tosic. 1999. Handbook of plant virus diseases. CRC Press, Boca Raton, FL.

 

Parthenolecanium corni, the European Fruit Lecanium

Larry Traubel, Grand Mesa Discount, Eckert, Colorado, provided this photo of Parthenolecanium corni, the European Fruit Lecanium on a peach tree. The photo shows the overwintering stage of the female scale and the small translucent crawlers.

Parthenolecanium corni

A horticultural oil sprayed when the crawler stage is present in spring will suffocate this insect. Timing the spray based on the presence of the crawlers before they begin to secrete their protective covering is critical. The crawlers typically hatch when Catalpa trees are in bloom.

The other option is to use a dinotefuran product that lists peaches or stone fruit on the label. Dinotefuran is a highly systemic third generation neonicitinoid applied as a trunk spray, foliar spray, or soil drench.