Integrated Pest Management Program Department of Plant Science and Landscape Architecture UConn Extension

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1 Integrated Pest Management Program Department of Plant Science and Landscape Architecture UConn Extension Late Easter 2017 presents growers with crop scheduling options Easter falls on April 16 in 2017, a late Easter date. Just as in the late seasons of 2014 (April 20), the 2017 schedule provides plenty of time for proper bulb programming as well as some extra time that growers will need to factor into their spring production plans. Last year Easter fell on a very early date (March 27 th ) and growers had to push hard all the way to the end to time the crop out properly. Pushing a crop hard to make an early Easter or pulling back hard to slow growth for a late Easter is not ideal and can diminish quality. Any added stress conditions tend to weaken plants which creates an opening for root disease and insect problems to gain momentum. This year the danger is that lilies will come in too early unless the extra time is managed properly. Here are some scheduling tips and options to consider for the 2017 crop. The ideal forcing schedule begins 23 weeks before Easter (Nov. 6 th for Easter 2017) and includes six weeks for bulb cooling and 17 weeks for lily development in the pot. This season, bulbs shipped in mid- October may arrive 25 weeks before Easter (Oct. 23), adding as much as two extra weeks to the schedule. You have several options for using this time. You can bring the crop in early and hold the lilies in cold storage for up to two weeks. This may be a good option for at least a portion of the crop since it will free up greenhouse space during a critical spring production period and most growers ship a portion of the lily crop starting around week two (April 2 nd in 2017). This option requires adequate cooler capacity and a heavy reliance on Fascination to prevent leaf yellowing. Also, cold storage for more than two weeks will reduce flower life and decrease plant quality. Since lily quality will diminish with prolonged storage times you ll need to consider other options for the majority of the crop. One option is to lose the extra time by dropping the temperature to 32-34F mid-way through the bulbcooling period. This will delay vernalization and allow you to start greenhouse forcing later without adding more than 1000 hours to the bulb chilling process. Alternatively you can make use of the extra time during bud initiation during the greenhouse forcing stage to increase secondary bud count. Timing the crop: The 2017 schedule is timed for saleable lilies one week before Easter. Adjust the schedule back for earlier shipping dates. If your bulbs arrive a week or two before the targeted Nov. 6 th start date you will have some extra time to the schedule. The extra time is manageable but plan ahead because it will be difficult to slow the crop down once the weather turns hot in late March and early April. Start lily programming immediately as soon as the bulbs arrive. Begin by inspecting and cleaning bulbs, removing any debris and damaged scales, especially scales that appear punky or show evidence of infection. For case cooled bulbs, make sure that the packing medium in the case is moist and move the bulbs into the cooler at 40-45F to begin the 6-week cooling or vernalization period. For pot-cooled bulbs, controlled temperature forcing (CTF) or natural cooling, plant bulbs in a well-drained medium and hold at 60-62F in the greenhouse for 3 weeks to stimulate root development before beginning the 6-week vernalization period. Give the full 3 weeks for proper root development since there is no need to skimp on time this year. Vernalization allows bulbs to produce a quality flowering shoot in a relatively short time. Six weeks of cooling is the standard-rule even though as little as 4-weeks of cooling will produce acceptable flowering.

2 With longer cooling periods (beyond 6-weeks), lily shoots emerge earlier and more uniformly, but leaf number, bud count, and the time from emergence to flowering are all reduced and average internode length increases. You can prolong the cooling period without adversely affecting later crop development by dropping the temperature to 32-34F as follows. Start cooling at 40-45F as normal but after 4 weeks drop the temperature to freezing or slightly above. The near freezing temperatures will suspend normal metabolism, putting the bulbs in a near dormant state during which additional vernalization will not occur. Bulbs can be held at this temperature until the extra time has elapsed, and then returned to 40-45F for the remainder of the 6-week vernalization period. Beware though, temperature must be carefully monitored and controlled with this technique. A light freeze of 32F will not harm the bulbs but colder temperatures may. If you only have 1-2 extra weeks in your schedule, I recommend you complete the normal 6-week cooling uninterrupted and make good use of the extra time to increase bud count later in the crop. With naturally cooled lilies follow the CTF schedule, but know your limitations on controlling temperatures -- especially during the vernalization period. You may not be able to hold the pots at 32-34F to delay vernalization. However, if these temperatures occur naturally you need to factor them into your schedule by subtracting any days that the bulbs experience 32F from the 1000 hour cumulative cooling period. Once vernalization is complete, reassess your schedule. If you still have extra time, try to increase secondary bud set with cool temperatures and keep a close rein on crop development with cool forcing temperatures. Begin greenhouse forcing as soon as the 6-weeks of bulb cooling is complete, but make sure you start no later than week 17 for case-cooled bulbs or week 14 for pot-cooled bulbs. Handle and pot case-cooled bulbs as previously described and immediately move them into the 60-62F greenhouse. Lilies begin emerging from 1 to 3 weeks after forcing begins record the emergence date (you will need it later for leaf counting) and, based on time of emergence, separate lilies into early, mid and late groups. Bud initiation starts immediately after emergence. You can increase bud set at this time by dropping the greenhouse forcing temperature for 7-14 days following primary bud initiation. The cool temperatures have the added benefit of slowing greenhouse forcing. Only use this technique if you start greenhouse forcing of casecooled lilies 18 to 19 weeks before Easter rather than the normal 17 weeks, or pot-cooled lilies 15 to 16 weeks before Easter rather than the normal 14 weeks. Run o F until primary buds initiate. Once primary buds are set, lower the greenhouse temperature to 46F for up to 14 days to stimulate secondary bud formation. After this period, raise the temperature to 60-62F until bud initiation is complete (mid- to late January). If greenhouse forcing started just one week ahead of schedule, limit the duration of the cool period to 7-10 days. The cool temperature treatment must start with primary bud initiation, which as a rule of thumb coincides with initial stem root development. When the roots just begin to break out of the stem (1/8 inch) that is a sign that bud initiation is starting. You must determine when primary bud initiation occurs to achieve the desired effect. Timing is critical since flower bud initiation may be adversely affected or delayed by temperatures that are lowered before bud initiation starts. In contrast, temperatures lowered after bud initiation is complete will have no beneficial effect on bud count but will slow overall crop development. Start leaf counting after bud set is complete and use temperature to control the rate of lily development during the remainder of the greenhouse forcing schedule. The rates of both leaf and flower development can be adjusted with temperature. For example, at 72F leaves unfold at a rate of 2 per day on average,

3 while at 63F the rate decreases to 1.5 leaves per day. Likewise, a lily will go from visible bud to bloom in 24 days at 81F, 31 days at 70F, 35 days at 64F and 42 days at 59F. If you arrive at visible bud 5 to 7 weeks before Easter and you can control temperature within these limits you should be in good shape to finish on time. Finally, plants that bloom early can be held in a cooler for up to two weeks. Storing finished lilies for longer than two weeks in not recommended. Leaf counting: As a reminder, the leaf counting technique is based on the fact that once flower buds initiate, leaf number is set and will not change. However, the exact number of leaves varies from year to year, and also with bulbs from different sources or bulbs exposed to different vernalization (bulb cooling) conditions. You already recorded the average date of emergence for the early, mid and late groups of lilies in your crop. Also record the average daily greenhouse temperature following shoot emergence. After bud initiation, select five lilies for every 1000 plants in each group (e.g. lilies grouped by bulb source, emergence time etc). Select plants representative of the overall crop, and then remove, count and record the total number of leaves. Use magnification and a needle to remove and count the smallest, un-expanded leaves. (Note: The shoot tip should show evidence of tiny flower bud formation. If this is not the case, you started counting too early. Wait one week and try again.) Record the number of fully developed leaves (those at a 45 o angle to the stem or greater) and the number of undeveloped leaves (those at an angle less than 45 o to the stem). Now, divide the number of fully developed leaves by the number of days since shoot emergence. This is the current rate of leaf development. Divide the number of undeveloped leaves by the number of days remaining until visible bud. This is the required rate of leaf development or the rate you need to maintain as you more forward in the schedule. If the current rate of development is too fast, indicating the crop will reach visible bud early, reduce the temperature in the greenhouse. If the current rate of development is too slow, indicating the crop will reach visible bud late, increase the average greenhouse temperature to speed development. Determine a new current rate each week (the rate since last count) and a new required rate. Determine the new required rate by subtraction - you do not have to destroy any more plants. Simply subtract the number of fully developed leaves from the average total number of leaves previously determined. HINT: Use a string tied around the stem, mark a leaf with a marking pen, or use a paper punch to mark the last leaf counted as fully developed on your indicator plants.

4 Figure 1: Leaf count starts as soon as bud initiation is complete. After total leaf count is established, no more lilies need to be destroyed. Just track the rate of leaf unfolding on indicator plants for the remainder of the schedule. Height control: Stem stretch tends to increase with low light, warm temperatures and long days. Expect long daylengths and warm temperatures in late-march and April. Crowding lilies or shading lilies with overhead baskets will increase the tendency for stretch. Growth regulators should not be applied until after flower buds have set and if you are running constant day/night temperatures at this stage as recommended the zero DIF effect should be adequate to control stretch. Unless used at very low concentrations, early growth regulator applications can reduce bud count. The DIF effect can be achieved with equal day/night temperatures, high night/low day temperatures or by dropping greenhouse temperature below the night-time set point for the first two hours at sunrise. To control lily height begin applying PGRs (A-Rest, Chlormequat E-Pro, Concise, Cycocel, Topflor or Sumagic) as needed when shoots are 3-5" tall. Split applications provide the best results. You can apply any of the PGRs at 1/8 to ½ normal rate, as needed, to control height.

5 Fig 2: Shading from overhead baskets will increase the tendency for lilies to stretch. During late season Easter dates, growers are under increased pressure for space to support spring crop production. Pest and disease management: Aphids, fungus gnats and bulb mites are a major concern on lilies. 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 GNL, and Rycar. 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 soil-borne 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). Disease and pest control: Before planting, clean bulbs of debris removing any scales showing evidence of infection or physical damage. 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

6 include Cleary s 3336, OHP GT, 26/36, Pageant Intrinsic, Emblem, Mural 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, Prestop and Triathlon BA or Double- Nickel (Triathlon BA and Double-Nickel have the same a.i.) 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. Preventing leaf yellowing: Monitor lilies for lower leaf yellowing, beginning one to two weeks before visible bud. Lower leaf yellowing often begins about the time buds first appear and becomes progressively worse over time. Apply Fascination or Fresco during greenhouse forcing if leaf yellowing is evident or has been a problem in the past. To prevent early-season leaf yellowing (seven to 10 days before visible bud) and midseason leaf yellowing (seven to 10 days after visible bud), spray Fascination (Fresco) at 5/5 to 10/10 ppm. Apply only to lower leaves and cover thoroughly. Figure 3. Once lily buds reach the puffy white stage they can be held in cold storage for 7-14 days. Pretreating to prevent disease and leaf yellowing is a helpful precaution. Prolonged cold storage prior to shipping and poor shipping conditions can also favor sudden, catastrophic yellowing. Plants that bloom early can be held in a cooler for up to two weeks, but I recommend an

7 application of Fascination or Fresco on lilies held in cold storage for more than seven days. Spray 100/100 ppm over the top of the plant when buds are about 3 inches long, but no more than 14 days prior to cold storage or shipping. Fascination and Fresco contains two active ingredients and recommended concentrations refer to both active ingredients. For example, a 100/100 ppm spray will contain 100 ppm BA plus 100 ppm GA4+7.] It is also prudent to spray for botrytis control prior to moving lilies to cold storage. Fungicides labeled for botrytis control include Veranda O, Phyton 27 and the biofungicide CEASE. Always follow label directions and test fungicides on a small group of lilies for damage to or residue on lily buds before using on the entire crop. Water Easter lilies thoroughly before starting cold storage. After removing from the cooler, place lilies in a shady location to avoid excessive wilting. Post-harvest flower life: EthylBloc can be used to extend lily flower life. EthylBloc is a plant growth regulator that is used to prevent early flower death caused by ethylene. Apply EthylBloc to plants with open or mature buds just prior to shipping. After the sprint-to-the-finish we had last year, the 2017 schedule should be a joy. You have plenty of time to pay attention to detail and bring the crop in right. Remember, to produce the best quality crop possible, stay on schedule and use preventive measures to check disease and insect problems early. Good luck in By: Richard J. McAvoy, Professor, Department of Plant Science and Landscape Architecture University of Connecticut Disclaimer for Fact Sheets: The information in this document is for educational purposes only. The recommendations contained are based on the best available knowledge at the time of publication. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. UConn Extension does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available. The University of Connecticut, UConn Extension, College of Agriculture, Health and Natural Resources is an equal opportunity program provider and employer.

8 2017 EASTER LILY SCHEDULE Weeks Forcing method Prior to Easter Date Case-Cooled Pot-Cooled (CTF) Oct Bulbs dug, shipped & in hand by end of October. Programming starts immediately. Treat bulbs for mites before cooling begins. See Notes on next page & accompanying article for details Oct. 23-Nov. 6 Start bulb programming as soon as bulbs arrive but no later than 23 weeks before Easter. (If started before week 23, see article for options for using the extra time). Cool at 40-45F for 6- weeks Pot and allow roots to grow at 60-62F for 3- weeks Nov Cool at 40-45F for 6-weeks Dec Pot no later than 17 weeks before Easter (If started earlier see week 13 instruction) Force in greenhouse at 60-62F Dec.25 Early plantings emerging & buds beginning to set. Jan 8 On later plantings, roots visible by wk 15 & shoots emerge by wk 14. Start fertilizing & keep moist. --- Force in greenhouse at 60-62F in pot. 13 Jan " tall. Apply fungicide drench as needed. Run 46F for 1 to 2 weeks to increase bud count BUT ONLY if lily programming started 1 to 2 weeks early & bud initiation has begun. See article for details. 12 Jan " tall. Bud initiation coincides with stem root development. Run 60-62Fday/night until bud set is complete. 11 Jan " tall. Apply growth regulator when 3-5 tall. Maintain temperature below 65F until bud initiation complete. 10 Feb. 5 Check for bud set. Begin leaf counting & graphical tracking. Keep house cool if ahead of schedule. 9 Feb " tall. Adjust temperatures as needed to maintain schedule. Space lilies to avoid yellow leaves & stretching. If leaf yellowing is evident, apply Fascination to lower leaves (7 to 10 days before visible bud). 8 Feb. 19 Check for aphids & root problems. Apply Marathon sometime during weeks 10, 9, or 8. Soil test & if leaf scorch is evident, use calcium nitrate for balance of schedule. 7 Feb " tall. Lilies are about half final height. 42 days to sale. Buds can be felt. If buds are visible on early planting run 60F until finish. 6 Mar days to sale. Buds should be visible no later than 30 days prior to sale. Grade for uniformity as buds become visible. Apply Fascination if leaf yellowing seen or anticipated.

9 5 Mar. 12 Buds 0.5-1" long. 4 Mar. 19 Buds 1-1.5", some bending down. 3 Mar. 26 Buds 1.5-2" long. If aphids present, use a total release smoke or aerosol. 2 Apr. 2 Buds 2.5-4" long., some turning whitish. Stop fertilizing just before sale & apply clear water once. Store lilies at 35-45F to hold. Apply Fascination to entire plant prior to cold storage to prevent leaf yellowing. 1 Apr. 9 Ready to sell. Shade lilies once removed from storage. If needed, use EthylBloc prior to shipping. 0 Apr. 16 Easter 2017

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