Common Questions asked by growers regarding A-Rest* Plant Growth Regulator

1. What is A-Rest?

     A-Rest is a plant growth regulator for height control on container-grown ornamentals, foliage plants and bedding plants. Its active ingredient is called ancymidol, which makes up 0.0264 % of A-Rest solution. Formulated in a 250 mg per quart liquid, A-Rest is available in three sizes: quarts, 2.5 gallons and 30-gallon drums.

2. How does A-Rest affect plant growth?

     Absorbed by roots, leaves and stems, A-Rest inhibits gibberellin synthesis and activity, resulting in shortened stem internodes, and a more compact plant. 

     A-Rest is a very predictable plant growth regulator with a linear (dose/effect) rate of response. A-Rest has a broader spectrum and greater activity than Cycocel® or B-Nine®, and is less touchy than Bonzi® or Sumagic®, being more forgiving of errors by the applicator. A-Rest also gives you the confidence that the plants that you grow will perform once they are planted in the landscape by your consumers.

3. Does A-Rest have any secondary effects?

     Yes, the three main secondary effects that A-Rest has are that the treated plants require less water, are better toned and have a darker green leaf color. Other benefits that growers have noted are that plants treated with A-Rest have increased stem turgor, improved resistance to air pollutants, improved freezing resistance, all resulting from an overall slower growth rate.

4. What plants is A-Rest effective on?

     A-Rest is effective on a wide variety of container-grown ornamentals, foliage plants and bedding plants. These include bedding plants, bedding plant plugs, bulbs, Easter lilies, poinsettias, chrysanthemums and foliage plants.

5. Are there any plants that A-Rest would not be a good choice to use on?

     A-Rest is not for use on plants grown in the ground, due to high rates required for activity. In addition, growers have observed that A-Rest has little effect on geraniums and impatiens after transplanting. However, A-Rest does work very well on impatien and geranium plugs. A-Rest's best fit is on small but high value containerized plants with confined root systems, where height and plant form managed for optimum quality.

6. When should I apply A-Rest?

     As with any growth regulator, the best response occurs when it is applied to the plant while the plant is still small or young. As plants grow, much higher rates of A-Rest are required to maintain the same degree of height control. Growth Regulators are most useful when applied just prior to the plant's rapid growth phase.

7. How to I prepare a solution of A-Rest?

     Whether you decide on using A-Rest as a spray or a drench, preparing a solution of A-Rest to use is simple. 

     Spray Solutions: First, using a trial rate or a rate based on your past experiences with A-Rest, decide on the rate that you would like to use on your crop. Next, with the knowledge that one gallon of your solution applied uniformly as a spray will effectively treat a 200 square foot area, determine the amount of solution that you will need to complete your application. Refer to the A-Rest Plant Growth Regulator Rate Chart in order to quickly determine the correct amount of A-Rest to use. After making sure that your sprayer is clean and not contaminated with any foreign substances, fill the spray tank with half the required amount of water. Then, measure out the correct volume of A-Rest. In order to make sure that your solution contains the correct amount of A-Rest, we suggest that you use a graduated cylinder or other similar measuring device that has ounces and/or milliliters clearly marked AFTER you have added the A-Rest to your sprayer, add the remaining amount of water required to complete your solution.

     Drench Solutions: Again, using a trial rate or a rate based on your past experiences with

     A-Rest, decide on the rate that you would like to use on your crop. Refer to the A-Rest Plant Growth Regulator Rate Chart in order to quickly determine the correct amount of A-Rest to use.

     The only difference that you will encounter when preparing a solution to drench with is determining how much solution you will need. As you know, a one-gallon solution of A-Rest will cover 200 square feet as a foliar spray. However, when preparing a solution of A-Rest for use as a drench, you must calculate the amount of A-Rest solution to prepare in a different way. 

     First, determine how many pots are going to be drenched. Next, based on the size of the pots, determine how much solution per pot to apply using the following volumetric guidelines: 

4 inch pot / 2 ounces of solution per pot

6 inch pot / 4 ounces of solution per pot

8 inch pot / 10 ounces of solution per pot

10 inch pot / 25 ounces of solution per pot

12 inch pot / 40 ounces of solution per pot

     Once you determine how many pots need to be drenched and the amount of drench solution to apply to each pot, simply multiply the two numbers together to determine the total amount of solution to prepare to complete your application.

8. How do I apply the A-Rest solution to my crop?

     Unlike other plant growth regulators that are only absorbed through the stem and the roots, A-Rest gives you the added benefit of being able to apply it as a foliar spray. 

     When applying A-Rest as a foliar spray, make sure that you concentrate on spraying the foliage uniformly to the point of runoff, not to runoff. This is important because the A-Rest that reaches the soil surface as runoff will cause additional growth regulation from root uptake. The plants being treated should be actively growing and turgid, because wilted leaves will not absorb the chemical as well as turgid ones. In addition, you should apply A-Rest when the foliage is dry to avoid dilution of the chemical and to ensure that the chemical is absorbed quickly.

     A-Rest is quickly absorbed into the foliage of the plant. The use of a wetting agent is not needed or recommended. When applying A-Rest as a foliar spray, treated plants may be irrigated after the leaves have dried. This may take as little as a half hour depending upon the conditions present in the greenhouse at the time of application.

     If you decide to use A-Rest as a drench, make sure that the potting soil is uniformly moist before you make the application. This will ensure that the A-Rest you provide the root system with is distributed consistently throughout the potting media. A good way to achieve this is to apply the drench within 12-24 hours after watering the crop. Many growers will water the plants that are going to be treated on a given afternoon and will apply a drench application of A-Rest the following morning in order to achieve optimum results. If the soil media is too wet at the time of application, some of the active ingredient may be lost out of the bottom of the pot. If the soil media is too dry at the time of application, the chemical will likely not be distributed consistently throughout the root system or may run out the sides of the container. In addition, growers have discovered that the use of pine bark in the potting soil mix reduces the effectiveness of soil drench treatments of A-Rest and other plant growth regulators by as much as 25-100%.

9. What amount of A-Rest shall I use to achieve the optimum growth response?

     The amount of A-Rest required for an optimum growth response depends upon pot size, stage of growth, method of application, light intensity and varietal response. Species-specific cultural practices such as watering, potting media, fertilization and temperature will also affect the growth response to a given dosage. 

     Therefore, you should establish specific application rates based on small-scale treatments under actual use conditions and keep records as to plant species and variety sensitivity. 

     The optimum rate of A-Rest will vary to the plant species. We have assembled information from growers and University research that will help you to determine an initial trial rate on many different species of plants commonly grown in the greenhouse industry. In order to find out at what rate to begin a trial at on a specific crop, consult the Application Rates section. We have organized all of the various crops into five distinctive groups. There are five altogether, including Bedding/Flowering Pot Plants and Plugs, Perennials, Bulbs, Foliage, and Holiday Pot Crops. In addition to giving you the most common rates that growers will use of A-Rest on a particular crop, the guides also give you the best time to apply A-Rest along with any other notes that may be important to you. At this time, the guides concerning perennials and foliage crops do not contain a lot of detail. As we learn more, these guides will be updated accordingly. 

     In general, growers in the cooler, northern climates will use rates at the lower end of a given rate range, while growers in warmer, southern climates will use rates at the upper end. If you are still in doubt after consulting the information listed in the guides, please call 1-800-419-7779 in order to speak with a SePRO Ornamental Advisor.

10. What kind of data should I record when growing a particular crop?

     When it comes to keeping records for any given crop, there is a large variation among growers. When dealing with plant growth regulators, these are the most important items to keep a record of: 

1. Identification of the species and variety

2. Sowing and/or Transplant Date

3. Start Week/Finish Week

4. Treatment Dates/Rates

* If you purchase your plugs from another grower, try to find out what PGR(s) the plug grower used as well as the application dates/rates of the treatments.

5. Environmental Irregularities (extended period of cloudy weather or warm temperatures, etc.)

6. Cultural Irregularities (extreme pH levels, fertilizer levels, etc.)

7. Other (e.g. a note reminding you that the plugs were transplanted late or were stretched when they came in)

7. Use a Control for each crop grown. Set a few plants aside before treatment so that comparison can be made to the treated plants. This will allow you to determine the degree of effectiveness of your PGR program and will help you gauge when to apply the next application until you attain enough experience with using A-Rest on the particular crop.

11. What is the length of control that I should expect from an application of A-Rest?

     Growers can depend on A-Rest to provide height control from anywhere from one week to as long as 2-3 months. The length of control when using A-Rest will vary depending on many factors including, but not limited to the plant's growth rate, cultural practices, and the dosage applied. Achieving consistent results when using A-Rest comes mainly with experience and keeping accurate records on how a particular rate effects the growth rate, noting any variables that may be considered different from the norm, such as periods of excessive temperature or cloud cover as well as increases in the application of fertilizers to the plants. 

     On some species, one treatment of A-Rest may provide the height control that you desire. Depending upon the level of control you require, additional treatments with A-Rest may be necessary. Visible "stretching" of plant terminals indicates that the previous A-Rest treatment is wearing off. At this time, an additional treatment should be considered. Growers who commonly use B-Nine or Cycocel will observe that A-Rest will take effect faster than B-Nine or Cycocel and will hold the growth of the plant for a longer amount of time.

12. My distributor shipped me some A-Rest and during shipment it froze. Is the product still good?

     Yes, A-Rest that has frozen is still good product after it thaws. However, the concern when A-Rest freezes lies with the container since frozen liquids expand. If your A-Rest has frozen, check the container for cracks. If none are present, place it in an area where it will thaw. After the A-Rest has thawed, shake the container well before using.