Hop to it!

Easter 2016 falls on an early date, March 27. This is the earliest Easter since 2008, and Easter 2008 fell on the earliest date in 95 years (March 23). On average, Easter dates as early as March 26 only occur every 15 years. As with all early Easter schedules, bringing a lily crop in on time will be a special challenge and some time-saving choices will need to be made along the way.
 

What it means for growers

The early date presents one immediate problem. The ideal production schedule requires a full 23 weeks to complete, meaning growers will need bulbs in hand by Oct. 18, 2015, to run a normal forcing program and bring the crop in for the start of the Easter sales season. That is unlikely to happen this year because bulbs typically are not available until late October at best. This means that growers will have to cut corners in the schedule to hit the early 2016 date. Early Easters also target early ship dates, typically the week of March 20 or one week before Easter Sunday. Growers will need to complete the entire greenhouse forcing program under winter season weather conditions that include low sun angles, cold night temperatures and short daylengths for much of the crop. Such conditions make it more difficult and expensive to push the crop if you fall behind schedule.
 

Tips for success for the 2016 Easter lily crop:

The ideal forcing schedule

With both pot-cooled and case-cooled bulbs the full cropping schedule requires 23 weeks to bring the crop in one-week prior to Easter Sunday. Both cooling methods call for six weeks of bulb cooling or vernalization, three weeks of root and shoot development prior to emergence and 14 weeks forcing in the greenhouse after shoot emergence.

If you need to crimp on time to shorten the ideal 23-week schedule, start by identifying the critical steps as well as the steps that offer the best possible choices for making up lost time.
 

Pot-cooled bulbs

Ideally pot-cooled bulbs — this includes naturally-cooled bulbs — are potted as soon as they arrive, preferably by Week 23 on the schedule (Oct. 18) and then held at 60-62°F for three weeks. The potted bulbs are then cooled at 40-45°F for six weeks or until Week 14, at which time they are moved to the greenhouse for forcing. During the initial three weeks, starting on week 23, roots develop and the shoot meristem matures.

The physiological developments that take place during the initial three weeks at 60-62°F improve cold perception during bulb cooling (vernalization) and allow bulbs time to mature which helps to produce more uniform shoot development and flower response. However, this is the first place to cut if circumstances force a late start on the 23-week forcing schedule.

If this is the case for you, cut the initial three weeks down to one or two weeks. This will allow a little time for some root development to begin before cooling. That means you can jump in on the recommended schedule at Week 22 or 21 (Oct. 25 or Nov. 1) and still be in pretty good shape the rest of the way. It is important to make sure you get at least one week of pre-chilling bulb development at 60-62°F before starting vernalization.

Six weeks of bulb cooling at 40-45°F is the next key step. Ideally this step should start by Nov. 8 or Week 20. One thousand hours or six weeks of cooling is recommended as a general rule but lilies will sprout and bloom on a reasonable schedule with as little as four weeks of cooling. So if you need to make up additional time you can start cooling as late as Week 18 (Nov. 22) and substitute up to two weeks of insurance lighting to make up for any shortage in cooling hours.

It is important to get the full 1,000 hours because fully cooled bulbs produce fewer leaves before bud. Fewer leaves makes the greenhouse forcing stage shorter as well. However, you have an insurance option to play here. Therefore, count both the time at 40-45°F and the insurance lighting into your 1,000-hour calculation.

The final production phase is the greenhouse forcing; for pot-cooled bulbs this means 14 weeks in the greenhouse beginning Dec. 20, 2015 for the 2016 schedule. Growers should be very hesitant to shortchange the greenhouse-forcing portion of the schedule. That is especially true this year, and should be of particular concern to any grower who typically has to push hard to finish on time even with mid-date Easter schedules. Remember, with a very early date Easter it may be hard to force bud development with high temperatures in late February and early March. Therefore, the second place to cheat, if needed, is on the bulb-cooling portion of the schedule. Make sure you expose the potted bulbs to at least four weeks of cooling at 40-45°F (five weeks is even better if time permits), then use insurance lighting for up to two weeks, to make up the difference in lost cooling (more on insurance lighting later).
 

Case-cooled bulbs

Now, let’s look at the case-cooled crop. Again, the full ideal schedule calls for 23 weeks from start to finish. Typically case-cooled bulbs are placed in the 40-45°F cooler starting on week 23 or Oct. 18 this year. After six weeks, bulbs are potted and moved to the forcing greenhouse (at 60-62°F) beginning 17 weeks prior to Easter or Nov. 29, 2015. Shoots take longer to emerge with case-cooled bulbs, but should be up by week 14 or Dec. 20. The greenhouse-forcing phase of the schedule is the same as with the pot-cooled crop.

With case-cooled bulbs the critical dates are the onset of bulb vernalization (cooling at 40-45°F) and the start of greenhouse forcing. If you cool your own bulbs, you’ll know how late you got started. For example, if you do not receive your bulbs until Nov. 1 you will already be two weeks behind schedule. Here’s what I recommend if you are two or more weeks behind at the onset: Cool bulbs for at least four weeks, then pot and begin forcing. As shoots emerge, immediately begin insurance lighting for up to two weeks. If you are still behind, you will have to make up for lost time during greenhouse forcing but after bud initiation is completed.

If you buy in case-cooled bulbs, it will be important to know exactly how much cooling they received. You want the bulbs on hand so that you can pot and begin forcing by Week 17 (November 29). If you know or suspect that the six weeks of cooling was incomplete, be safe and use insurance lighting. If the bulbs arrive after Nov. 29, you will have to make up time during greenhouse forcing but after bud initiation.
 

Greenhouse forcing

With both pot-cooled and case-cooled lilies, greenhouse forcing starts at the end of the bulb-cooling period. Typically this is 17 weeks before Easter for case-cooled bulbs and 14 weeks before Easter for pot-cooled bulbs. The difference in the two schedules just reflects the stage of shoot development. With pot-cooled bulbs the shoots are either at the soil surface or already emerged as soon as forcing begins (Week 14). In contrast, case-cooled bulbs will take up to three weeks to emerge. So either way, the shoots on both crops should be emerging by about Week 14 (Dec. 20).

Bud initiation begins soon after lilies emerge, and should be completed no later than mid-January in the 2016 crop, when shoots are 3-5 inches tall. The development of stem roots coincides with flower bud initiation. During this period, day and night temperatures of 60-65°F are desirable (63°F is ideal), but it is imperative that temperatures do not exceed 65°F until bud initiation is complete. This is important — don’t try to catch up with high temperatures at this point in the schedule. If you find yourself short on forcing time in the greenhouse, wait until bud set is complete before attempting to speed up plant development with higher temperatures. Look for tips on leaf counting and greenhouse forcing in the October issue.
 

Insurance lighting

Insurance lighting refers to night break lighting used to produce a long day photoperiod effect. When applied starting immediately at shoot emergence, the long-day photoperiod has the same effect as bulb cooling. It reduces the time to flower as well as the number of leaves and flowers produced. The reduced flower number is a negative consequence that we accept as a trade-off in order to make the plants flower in a reasonable time frame. Therefore, insurance lighting can be used to substitute for inadequate bulb cooling. Provide one week of insurance lighting for each week of lost cooling — up to a total of two weeks. For example, if bulbs arrive too late to begin case-cooling on Week 23, or if weather conditions prevent you from achieving 1,000 hours of natural pot-cooling by Week 14 or Dec. 20, you can still start greenhouse forcing on time by providing a week of insurance lighting for each week of lost cooling time. Incandescent, fluorescent, LED or HID lighting in excess of 10 foot-candles from 10 p.m. to 2 a.m. daily will provide the necessary night break.

It is important that the shoots perceive the long day photoperiod (the insurance lighting) as soon as they emerge. And because lilies do not emerge all at once, growers should gather groups of lilies as they emerge and begin insurance lighting. Gather pots with emerging shoots two to three times per week and make note of how long each block receives the insurance lighting. This is preferred since insurance lighting will also cause stretching, therefore excessive lighting of more than two weeks will provide no additional benefit in terms of vernalization and will only serve to produce taller lilies with fewer buds. Note that the insurance lighting period will coincide with lily bud initiation so keep day/night temperatures between 60-65°F during this period.
 

Nutrition

Proper nutrition is also important in early crop development. Inadequate nitrogen early in development leads to small bottom leaves, and small leaves limit the potential for subsequent growth. To get plants off to a good start, provide a single application of 400-600 ppm nitrogen at first irrigation as lilies begin to emerge. This will help to stimulate early leaf development. Remember that the more leaf area a plant has, the more sunlight the leaves will gather, and that translates into greater growth. Phosphorus is also important in early lily development. Older recommendations withheld phosphorus nutrition in lily to avoid leaf scorch caused by fluoride toxicity. (Fluoride is found in phosphorus based fertilizers and some soil amendments). But phosphorus is also important for strong root development. Use a complete fertilizer formulation, such as a 20-10-20, for the initial feed.

After the initial feeding use a 15-0-15 formulation, but if phosphorus was not added to the medium use the 20-10-20 formulation on an alternating basis with the 15-0-15. Fertilizer rates should range from 200-400 ppm. Do not allow medium EC to exceed 3-3.5 mmho/cm based on a Saturated Media Extract. Periodic nutrient testing is advisable during the crop. Testing the nutrient status of young but fully expanded leaves will provide the most accurate picture of lily nutritional status. Leaf tissue nutrient content should fall in the following ranges, 2.4-4% nitrogen, 0.1-0.7% phosphorus, 2-5% potassium, 0.2-4% calcium, 0.3-2% magnesium, 100-250 ppm iron, 50-250 ppm manganese, 30-70 ppm zinc, 5-25 ppm copper, 20-50 ppm boron.
 

Managing disease, pests and other problems

Before planting, clean bulbs of debris removing any damaged scales, especially scales that show evidence of infection. Once potted, root rots associated with Rhizoctonia, Fusarium and Pythium are a concern. Drench immediately with Banrot, Pageant Intrinsic or Empress Intrinsic, broad-spectrum fungicides, or you can treat to control these diseases separately by selecting from the fungicides specifically registered for Rhizoctonia, Fusarium and Pythium control on lily. Materials registered for Rhizoctonia and/or Fusarium include Cleary’s 3336, OHP 6672 26GT, 26/36 and many generics such as Pageant Intrinsic and Contrast (Rhizoctonia) and Terraclor (Rhizoctonia).

Materials registered for controlling Pythium include Alude, Banol, Subdue Maxx (beware of using mefenoxam exclusively because of widespread fungicide resistance issues with this active ingredient), Segway O and Truban. Check with manufacturers regarding compatibility when tank mixing fungicides. Fungicides may need to be re-applied later in the crop. Check labels for guidance.

Preventative biological fungicides (RootShield, Rootshield Plus, CEASE, Actinovate, Mycostop, Companion and Triathlon BA) may be applied at planting for disease suppression and to enhance root growth. Check with company or product labels information for safe time intervals between application of biological agents and chemical fungicides.

Aphids, fungus gnats and bulb mites are a major concern. Many chemicals are listed for aphid control, including: Safari, Flagship, Tristar, Marathon and many generics, DuraGuard, Enstar AQ, Suffoil X, Insecticidal Soap, , M- Pede, Kontos, Endeavor, Aria, Mainspring, Rycar and XXpire. Fungus gnats can be controlled with some of these same chemicals as well as Citation, Distance, Adept, Pylon, insect parasitic nematodes (Nemasys, NemaShield, Scanmask, Entonem) and Gnatrol WDG. Bulb mites, Rhizoglyphus robini, represent one of the more troublesome insect pests on lilies and effective management requires an integrated approach. Bulb mites are considered a secondary pest and are commonly associated with decay caused by fungus gnat damage and soilborne fungal pathogens. The soil dwelling predatory mite, Hypoaspis aculeifer, may help suppress bulb mites. Note: Registration of pesticides varies by state so consult and follow labels for registered use. To avoid any potential phytotoxicity or residue problems, spot test before widespread use. No discrimination is intended for any products not listed.

Even experienced growers should anticipate that the 2016 schedule will be a challenge. How big a challenge it is will depend on when the bulbs arrive and the physiological condition they are in when you start your schedule. You won’t know any of this until the digging season is complete. Regardless, anticipate a very tight schedule for Easter 2016 and the need to cut a few corners to make this crop on time. Before the season starts, make sure your insurance lighting system is ready to go and decide where in the schedule you want to cheat for time. Once started, stay on top of crop development by tracking leaf unfolding and bud development. You don’t want to fall behind too far or you may not be able to catch up. As was the case in 2008, 2016 is a leap year so you do have one extra day. Good luck and have a profitable Easter in 2016.

Watch for the second part of this two-part production series in the October issue.

Richard is professor and extension specialist at the University of Connecticut.