P&PDL Picture of the Week for
February 11, 2008

Avoiding the Easter Lily Production “Blues” 

Roberto G. Lopez, Ph.D., Assistant Professor & Floriculture Extension Specialist, Purdue University

Janna Beckerman, Ph.D., Assistant Professor & Plant Pathology Specialist, Purdue University

With an early Easter fast approaching (March 23rd) growers can avoid root rots, lower leaf yellowing and flower abortion by the management practices they implement now. Easter lilies have the potential for developing root rot during vernalization and greenhouse production.  It is important to routinely remove plants from their pots and visually inspect the roots. The roots should have white root tips (Figure 1) and any browning is likely a root rot pathogen.  Preventive fungicides should be used on a regular schedule (every four to six weeks) to prevent Pythium, Phytophthora, and Rhizoctonia, especially late in the crop cycle.  It is important to rotate between chemical classes to prevent fungicide resistance.  The following fungicide drenches are recommended (Always consult labels carefully for exact rates and to see if the material is registered in your state):

Fungicide FRAC CODE Rate
Banrot 1 + 14 8 oz/100 gal water
Clearys 3336 1 8 oz/100 gal water
Chipco 26019 2 Refer to label
Subdue MAXX 4 1/2 oz/100 gal water
Truban 30 WP 14 3 to 10 oz/100 gal water

Lowering leaf yellowing and leaf drop is commonly observed from visible bud to flowering in a tightly spaced crop or one that has been heavily treated with growth regulators (Figure 2).  An early-season application of Fascination or Fresco [gibberelins (GA4+7) and cytokinin (Benzyladenine 6BA)] 1 week before and 1 week after visible bud to the lower leaves will prevent lower leaf yellowing.  Do not apply to the upper leaves as stem elongation can occur.  A late-season application to the foliage and buds is recommended when the largest bud is 8 cm in length to reduce lower leaf yellowing and prolong post harvest life.  Plants treated with either Fascination or Fresco maintain green lower leaves (Figure 3). The following table has suggested rates of Fascination and Fresco (again, carefully consult the label):

Application Rate (6BA/GA4+7) Ml or (oz) of Fascination or Fresco per 1 gal. water
Early-season 10/10 ppm 2.1 ml (0.07 oz)
Late-season 100/100 ppm 21 ml (0.71 oz)

Although your crop may be behind schedule, remember that forcing temperatures above 75 °F can lead to flower bud abortion in Easter lilies (Figure 4). The rate of plant development from visible bud to flowering is only linear between 57° and 72 °F.  For example, increasing the average daily temperature from 55 °F to 60 °F decreases time to flower by 4 days (Table 3).  An increase in temperature from 80 °F to 85 °F results in only a one-day decrease in time to flower.  Table 3 shows the predicted time from visible bud to flower at average daily temperatures ranging from 55 °F to 85 °F.

Average daily temperature ( °F)
Days from visible bud to flower
55
42
60
38
65
34
70
31
75
27
80
25
85
24

Click image to enlarge

Figure 1. White root tips

Figure 2. Lower leaf yellowing
Photo courtesy of Allen Hammer

Figure 3. Plants treated with Fascination

Figure 4. Flower bud abortion
Photo courtesy of Erik Runkle

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service