Ornamental Horticulture Monthly Newsletter
Volume 2 No. 2, April 1999

Resistance of various perforated plastic sleeve types to CO2 diffusion
R. D. Berghage

Abstract

The resistance of 3 sleeve types to diffusion of respiratory CO2 produced by chrysanthemums was evaluated. Plants in open air or packaged in perforated plastic sleeves maintained gas concentrations within the plant canopy equal to ambient CO2. Respiratory CO2 accumulated in plants packaged in paper or fiber sleeves.

Introduction

Greenhouse grown pot chrysanthemum plants are sleeved prior to shipping to reduce handling damage during packing and transport. A wide variety of sleeve types are available for this purpose. Some of the more common materials used to manufacture sleeves are: clear or colored plastic films, paper and spun fibers. Properties considered desirable for a sleeving material include strength, resistance to moisture and ability to "breathe". The ability to breathe, or a lack of resistance to gas diffusion, is a somewhat nebulous concept of unproven utility, however manufactured sleeves are often marketed based on this property. This experiment was undertaken to determine if differences in diffusion of respiratory gases through different sleeve types could be detected and if so, which sleeve types offer the least resistance.

Materials and Methods

Chrysanthemum plants in 6.5 inch plastic pots were obtained from Aldershot of New Mexico from 2 regular shipments prior to sleeving and boxing. Plants of a variety of cultivars were sleeved in either a brown paper sleeve, a perforated plastic sleeve, a spun fiber sleeve, or were not sleeved. Gas sampling tubes were inserted into the canopy of each plant. Gas samples were withdrawn and analyzed daily for six days. Samples were analyzed for CO2 using and infra-red gas analyzer (ADC inc.). Statistical analysis were performed using BMDPpc.

Results and Discussion

Respiratory CO2 accumulated within the canopy of plants sleeved with either paper or spun fiber sleeves. In excess of 100ppm difference CO2 concentration between inside and outside the sleeves was observed in some cases. This represents a significant resistance to diffusion caused by the sleeves. This trend was observed in all cultivars, sampling dates, and with both harvests. In contrast respiratory CO2 was not accumulated in plants sleeved with a perforated plastic sleeve. Clearly the size and number of perforations was more than adequate to provide adequate gas exchange.

The paper sleeves used were a relatively heavy brown paper with no perforations, and it was not surprising that they offered resistance to gas exchange. The fiber sleeves o the other hand, look like they would offer little or no resistance to gas exchange. These fiber sleeves, were however no better than paper sleeves in their ability to breathe.Although it is clear that the marketing claim of fiber sleeve manufacturers that their product breathes well is incorrect at least with regard to carbon dioxide, it is not clear that this is detrimental to plant longevity. One clear exception would be resistance to diffusion of ethylene. Although not measured there is no reason to believe that resistance to ethylene diffusion would differ substantially from that of respiratory CO2.

Conclusion

Spun fiber sleeves do not breathe better than plain paper sleeves and offer more resistance to gas diffusion that perforated plastic sleeves. The decision to purchase spun fiber sleeves should be based on criteria other than ability to breathe.

Evaluation of Weed Control and Productivity on Field Grown Cut Flowers
E. Jay Holcomb, Tracey L. Harpster, Robert D. Berghage, and Larry J. Kuhns*

Introduction
A set of studies was established in the summer of 1998 to determine the tolerance of field grown cut flower species to specific preemergence herbicides, the effectiveness of weed control by those materials, and to determine if productivity of cut flowers is affected either by the herbicides or by colored mulches.


Methods and Materials

The first study was conducted at the Penn State University Horticulture Research Farm at Rock Springs, PA. Four commercially grown cut flower species were used in this experiment: celosia (Celosia argentea L. 'Red Rocket'), sunflower (Helianthus annuus L. 'Schmitz Gold'), cosmos (Cosmos bipinnatus Cav. 'Red Qis'), and strawflower (Helichrysum bracteatum (Venten.) Andr. 'Choice Mix'). Treatments consisted of a control, the preemergence herbicide treatments listed in Table 1; and silver, red, and white plastic mulch. They were replicated three times for each species, with six or ten plants per rep depending on the species. All plots were in raised beds. There were four beds, each about 80 feet long by 30 inches wide. An eight-foot grass walkway separated the beds. A randomized complete block design was used, with each treatment by species block measuring 3 ft by 30 in. There was an extra one-foot between treatments within the bed.

The sunflowers, cosmos and strawflowers were planted on June 12, and the celosia was planted on June 24. All beds were hand weeded before herbicide applications on July 2. Conditions at the time of application were clear and sunny with 3 to 5 mph winds. The air temperature was 80º F and the soil temperature was 69º F. Time of application was 9:00 to 10:00 am. Prodiamine and napropamide were applied over-the-top with a CO2 test plot sprayer at 30 psi through an 8004E nozzle at 35 gallons per acre. An Acme Spread Rite applicator was used for the OH-2 treatments. Approximately 1 week after treatment (WAT) the foliage of the control and herbicide treated plants was examined and evaluated. Other evaluations included injury and plant quality ratings at 4 WAT and the harvesting and measurement of the flower number, length, and weight at 4, 7 and 11 WAT.

The second study was conducted at McCreight¹s Wholesale Florist, Washington Boro, PA, a commercial field grown cut flower producer. The site had been plowed and disked. Plants were transplanted on: May 12, statice (Limonium perezii (Stapf) F.T. Hubb. 'Seafoam Statice'); May 22, celosia (Celosia argentea L. 'Crested Cockscomb'); and May 26, feather kale (Brassica oleracea L. var acephala 'Glockner Today'), and zinnia (Zinnia elegans Jacq. 'Cherry Ruffle'). A randomized complete block design was used. Celosia, kale, and statice plots were approximately 3 ft by 8.5 ft, with five plants in each plot. The zinnia plots were 3 ft by 6 ft and contained four plants per plot.

On May 27, 1998 the treatments in Table 2 were applied with a CO2 test plot at 30 psi through an 8004E nozzle in the equivalent of 35 gallons per acre. The conditions at the time of application were 85-90º F with a slight breeze of 3 to 9 mph. At the time of application the plants were the following heights: zinnia, 3 to 6 in; celosia, 4 to 8 in; feather kale, 3 to 5 in; and statice, 6 to 12 in. Weed control data, plant quality and herbicide injury ratings were collected on June 25 (4 WAT) and July 21 (8 WAT).

Results and Discussion
Experiment 1. One WAT sunflowers were not affected by OH-2, napropamide caused slight injury, but prodiamine caused serious injury (Table 1). The newly expanded leaves at the time of application had chlorotic spots with a necrotic spotin the center. Prodiamine is not labeled for use on sunflowers and this may be the reason. Cosmos was not damaged by any of the herbicides even though it is not on the label of any of the herbicides. Strawflowers and Celosia had a fair amount of deformed leaves, but the damage was observed on the controls also, so it could not be correlated to any of the herbicide treatments.

At 4 WAT all of the treatments provided excellent weed control in the cosmos and strawflower (Table 3). Weed control in the sunflowers was very good to excellent. Only the silver and red mulch plots had statistically more weeds than the control, 6.7 and 5.7% weed cover, respectively. Weed species present in these plots included large crabgrass (Digitaria sanguinalis (L.) Scop.), common chickweed (Stellaria media (L.) Vill.), giant foxtail (Setaria faberi Herrm.), redroot pigweed (Amaranthus retroflexus L.),common lambsquarter (Chenopodium album L.), black nightshade (Solanum nigrum L.), common dandelion (Taraxacum officinale Weber in Wiggers),purslane (Portulaca oleracea L.), yellow woodsorrel (Oxalis stricta L.), and Canada thistle (Cirsium arvense (L.) Scop.). Weeds were growing through the planting holes in the plastic mulch treatments in the sunflowers only. In the celosia all of the treatments provided excellent weed control except the prodiamine, in which there was 31% weed cover. Weeds in these plots included large crabgrass, purslane, oxalis, shepherds-purse (Capsella bursa-pastoris (L.) Medicus), mouseear chickweed (Cerastium vulgatum L.) scarlet pimpernel(Anagallis arvensis L), and Virginia copperleaf (Acalypha virginica L).

At 4 WAT the quality ratings for the cosmos and strawflower were all uniformly high, and the injury ratings low, regardless of treatment. The napropamide, prodiamine, and OH-2, with and without mulch caused slight injury to the sunflower, but did not result in lower quality ratings. In the celosia, the prodiamine and OH-2, with and without mulch, caused moderate injury that resulted in lower quality ratings for the injured plants. The number and weight of primary and secondary sunflowers harvested were not affected by any of the treatments (Table 4). The average length of the primary inflorescences was shorter in the prodiamine and the silver and white mulch treatments.

The number, average length, and total weight of cosmos flowers harvested were not affected by any of the treatments.

The number and weight of strawflowers harvested were not affected by any of the treatments, but the average length of the inflorescences was shorter in the napropamide treatment. Though there was considerable variation in the number and total weight of flowers cut, it did not turn out to be statistically significant. This may have been because there was a great deal of variation in the productivity of each plot that may have masked differences between treatments.

OH-2 with mulch was the only treatment that reduced the number and total weight of celosia flowers harvested. Average stem length was not affected.

In summary, except for OH-2 with mulch on celosia, when compared to the weeded control none of the herbicide or mulch treatments affected the harvested number or weight of any of the flowers.

Experiment 2. At 4 WAT all of the herbicide treated plots had significantly less weed cover than the untreated control plots (Table 2). Both rates of oryzalin, napropamide and pendimethalin; and OH-2 without mulch; provided excellent weed control. The high rate of prodiamine and the OH-2 with mulch provided good control. The low rate of prodiamine and both rates of trifluralin provided moderate to poor weed control. Giant foxtail seedlings, and hairy galinsoga (Galinsoga ciliata (Raf.) Blake.) were the predominant weeds in these plots.

Though there was variability between species, at 8 WAT the oryzalin and napropamide treatments were still providing better overall weed control than the other treatments. The high rate of oryzalin consistently provided excellent control while the low rate provided good control. With a few exceptions the other treatments did not provide an acceptable level of control. Because the statice plots were heavily infested with Canada thistle, the cooperator hand weeded the area to reduce seed production and spread of this noxious weed; therefore, this species was not included in the 8 WAT evaluation.

At 4 WAT the pendimethalin at 4 lbs. ai/A injured all of the plants, and at the 2 lb.ai/A rate injured all but the zinnia (Table 5). Oryzalin did not injure any of the plants compared to the control except for slight injury to celosia when applied at the 4 lb. ai/A rate (Table 5). Both rates of napropamide injured the celosia, and the high rate slightly injured the zinnia. The OH-2 without mulch caused slight injury to the celosia and zinnia; and with mulch slightly injured the statice. Neither prodiamine nor trifluralin caused any injury to any of the plants at 4 WAT.

At 8 WAT the pendimethalin still caused more injury than any of the other treatments (Table 5). Celosia, kale, and zinnia treated with the high rate, and kale treated with the low rate, exhibited injury symptoms. Zinnia treated with the high rate of oryzalin or trifluralin, and celosia treated with the high rate of prodiamine, were slightly injured. The oryzalin, prodiamine, and triflualin treatments did not injure any of the other plants. None of the plants treated with either rate of napropamide exhibited injury symptoms 8 WAT. OH-2 with mulch slightly injured statice, and OH-2 without mulch slightly injured zinnia.

At 4 WAT pendimethalin at the high rate reduced the plant quality of all of the species tested, and the low rate reduced the quality of all except the zinnia. None of the other treatments reduced the quality of the kale, statice, or zinnia except the OH-2 without mulch, which affected the zinnia. However, the quality of the celosia was reduced by the OH-2 without mulch, the high rate of oryzalin, and both rates of napropamide and prodiamine.

At 8 WAT, the high rate of pendimethalin reduced the quality of all of the plants except the statice. The low rate affected only the kale. The high rate of oryzalin reduced the quality of celosia and zinnia and the high rate of prodiamine reduced the quality of celosia.

In summary, pendimethalin provided excellent early season weed control, but poor late season control. It consistently caused injury at 4 lbs ai/A and sometimes at the 2 lbs ai/A rate. Oryzalin provided good to excellent weed control, but slightly injured celosia and zinnia when applied at 4 lbs. ai/A. Napropamide provided excellent early season weed control marginally acceptable weed control later in the season. Though it caused some injury to celosia early in the season when applied at the high rate, no injury to any of the plants was observed later in the season. Prodiamine and trifluralin were the overall safest of the herbicides, but they provided the weakest weed control. OH-2 was very effective when placed on the soil surface, but was less effective when placed on an organic mulch. The organic mulch was designed to keep the OH-2 particles from splashing on to the crop plant and injuring the plants. OH-2 tended to be safer placed on a mulch than on the soil surface, but statice was slightly injured even when a mulch was used.

Table 1. Herbicide treatments were applied on sunflower, strawflower, celosia and cosmos on July 2, 1998. The percentage of leaves that appeared either deformed or damaged were recorded one week after treatment.
Treatment (lbs. ai/A) Sunflower StrawflowerCelosia Cosmos
No Chemical (control) - 0 12 8 0
(OH-2) Oxyfluorfen 3 2 10 12 0
+ Pendimethalin (mulch)
(OH-2) Oxyfluorfen 3 0 10 25 0
+ Pendimethalin (no mulch)
Napropamide 50WP 4 13 33 12 3
Prodiamine 65WDG 1 50 17 10 0

Table 2. Weed control in field grown cut flowers. Values represent the percent of the soil covered by weeds averaged over all four species rated 4 WAT, and the percent of soil covered by weeds averaged over three reps for celosia, kale and zinnias, rated 8 WAT.
Rate 4 WAT 8WAT 1/
Treatment Lbs/A Average Celosia Kale Zinnia
Control 0 86.7 a 100 100.0 a 100
Oryzalin 4AS 2 1.7 f 45.7 bc 21.7 cd 13.7 bc
Oryzalin 4AS 4 0.3 f 15.0 cd 6.7 d 7.0 c
Napropamide 50WP 3 7.0 def 91.0 a 33.3 cd 27.0 bc
Napropamide 50WP 6 7.6 def 40.0 bcd 53.3 c 3.3 c
Prodiamine 65WDG 0.65 34.4 b 90.0 a 100.0 a 38.3 abc
Prodiamine 65WDG 1.5 17.1 cde 87.3 a 100.0 a 30.0 bc
Pendimethalin 60WDG 2 4.3 ef 91.7 a 75.0 ab 45.0 abc
Pendimethalin 60WDG 4 1.5 f 46.7 bc 60.0 abc 23.3 bc
Trifluralin 5G 2 32.8 b 99.3 a 93.3 ab 43.3 abc
Trifluralin 5G 4 26.8 bc 98.3 a 90.0 ab 56.7 ab
(OH-2) Oxyfluorfen 3 18.9 cd 75.0 ab 95.0 a 80.0 a
+Pendimethalin (mulch)
(OH-2) Oxyfluorfen 3 0.2 f 7.5 d 87.5 ab 55.0 ab
+Pendimethalin (no mulch)
1/ Means within columns, followed by the same letter, do not differ at the 5% level of significance (DMRT)

Table 3. Weed control, quality and injury of sunflower, cosmos, strawflower, and celosia treated with herbicides or colored mulches, rated 4 WAT. Percent weed coverage is the percent of the soil covered by weeds. Quality represents the vigor and freedom from damage of the crop; 1 = dead and 10 = excellent condition. Injury represents the amount of chlorosis or necrosis on the plant; 1 = no injury and 10 = dead.
Sunflower Strawflower Celosia 1/
% Weed % Weed % Weed
Treatment Coverage Quality Injury Coverage Quality Injury Coverage Quality Injury
Weeded Control 0 c 10.0 a 1.0 c 0.0 a 10.0 a 1.0 a 0.0 a 10.0 a 1.0 b
Silver Mulch 6.7 a 10.0 a 1.0 c 0.0 a 10.0 a 1.0 a 0.3 a 9.7 a 1.0 b
Red Mulch 5.7 ab 10.0 a 1.0 c 0.0 a 10.0 a 1.0 a 0.0 a 10.0 a 1.0 b
White Mulch 0.3 c 9.3 a 1.0 c 0.3 a 10.0 a 1.0 a 3.3 a 10.0 a 1.0 b
(OH-2) Oxyfluorfen 1.0 c 10.0 a 2.0 b 0.3 a 9.0 a 1.3 a 5.0 a 6.3 b 4.7 a
+Pendimethalin
(0H-2) Oxyfluorfen 2.0 bc 9.7 a 2.7 a 0.3 a 10.0 a 1.0 a 5.7 a 7.7 b 3.3 a
+Pendimethalin
Napropamide 50WP 4.0 abc 10.0 a 1.7 b 1.7 a 9.0 a 1.3 a 7.0 a 9.3 a 1.3 b
Prodiamine 65WDG 2.0 bc 9.3 a 3.0 a 1.0 a 9.0 a 1.7 a< 31.0 a 7.3 b 3.7 a

Table 4. Effect of herbicides and mulches on the average length and total number and weight of primary inflorescences of sunflowers, and all inflorescences of strawflowers, celosia and cosmos over three reps. Flowers were harvested on July 30, August 20, and September 15, 1998 (4, 7 and 11 WAT).
Sunflower Strawflowers Celosia
# of Average Total # of Average Total # of Average Total
Treatment Flowers Length Weight Flowers Length Weight Flowers Length Weight
(in.) (gm.) (in.) (gm.) (in.) (gm.)
Primary or Terminal Inflorescence 8 26.2 4652 37 23.3 1986 36.7 19.6 2971
Weeded Control 9 23.3 4317 58 22.7 2698 46 20.4 4674
Silver Mulch 8 26.6 4513 56 23.6 2622 46.3 19.2 4124
Red Mulch 9.3 22.3 3475 68 22 2444 40.3 21.3 3659
White Mulch 8 27.5 3691 42 23.5 1866 18 18.8 1520
(OH-2) Oxyfluorfen
+Pendimethalin(mulch) 7 24.8 3315 51 23.2 2333 30.3 18.5 2203
(OH-2) Oxyfluorfen
+Pendimethalin(no mulch) 8 24.4 4075 39 18.2 1559 41.7 18 3130
Napropamide 50WP 8.3 21 3169 55 21.8 2442 24.7 18.7 2429
Prodiamine 65WDG NS * NS NS ** NS * NS **
Significance of F NS 2.7 1.6 18.3 1368
LSD at 0.05

Table 5. Plant injury for celosia, kale, statice, and zinnia rated on June 25 (4 WAT) ,and on July 21, 1998 (8 WAT). A value of 1 = no injury and a value of 10 = dead.
 
Celosia
Kale
Statice
Treatmentlbs./A
WAT8 WAT
Control0
Oryzalin 4AS2
Oryzalin 4AS4
Napropamide 50WP3
Napropamide 50WP6
Prodiamine 65WDG0.65
Prodiamine 65WDG1.5
Pendimethalin 60WDG2
Pendimethalin 60WDG4
Trifluralin 5G2
Trifluralin 5G4
(OH-2) Oxyfluorfen3
+Pendimethalin (mulch)
(OH-2) Oxyfluorfen3
+Pendimethalin (no mulch)
4 WAT8 WAT
4 WAT8 WAT
1.3 de1.4 cd
1.3 de2.1 cd
2.8 bc2.4 bc
3.0 bc1.5 cd
3.4 b1.5 cd
2.2 cd2.3 cd
2.3 cd3.5 b
3.7 b2.6 bc
5.7 a4.7 a
1.0 e1.8 cd
1.0 e1.1 d
1.3 de1.4 cd
  
2.7 bc1.8 cd
  
4 WAT8 WAT
  
1.0 b1.0 b
1.1 b1.1 b
1.1 b1.1 b
1.0 b1.0 b
1.0 b1.1 b
1.0 b1.3 b
1.0 b1.0 b
3.5 a5.2 a
4.1 a4.6 a
1.0 b1.0 b
1.0 b1.3 b
1.2 b1.0 b
  
1.7 b1.0 b
  
4   
  
1.0 b1.0 b
1.0 b1.5 b
1.0 b1.6 b
1.1 b1.9 b
1.0 b2.1 b
1.1 b1.1 b
1.0 b1.2 b
1.5 a1.3 b
1.7 a1.4 b
1.1 b1.6 b
1.0 b1.2 b
1.6 a3.5 a
  
1.0 b1.0 b
  
1/ Means within columns, followed by the same letter, do not differ at the 5% level of significance (DMRT)

Table 6. Plant quality for celosia, kale, statice and zinnia rated on June 25 (4 WAT) and July 21, 1998 (8 WAT). A value of 1 = dead and a value of 10 = top quality.
Celosia Kale Statice
Treatment lbs./A 4 WAT 8 WAT 4 WAT 8 WAT 4
WAT 8 WAT 4 WAT 8 WAT
Control 0 9.5 a 9.2 abc 10.0 a 10.0 a 9.6 abc 8.7 a
Oryzalin 4AS 2 8.7 ab 8.5 abcd 9.2 a 9.9 a 9.8 a 9.5 a
Oryzalin 4AS 4 7.5 cd 7.8 cd 9.7 a 9.9 a 9.8 a 9.3 a
Napropamide 50WP 3 8.0 bc 9.3 abc 10.0 a 10.0 a 9.9 a 9.1 a
Napropamide 50WP 6 6.9 de 9.1 abc 9.9 a 9.9 a 9.7 a 9.1 a
Prodiamine 65WDG 0.65 8.4 bc 8.4 abcd 9.8 a 9.7 a 9.7 a 9.7 a
Prodiamine 65WDG 1.5 8.0 bc 7.5 d 9.7 a 10.0 a 9.7 a 9.5 a
Pendimethalin 60WDG 2 6.5 e 8.1 bcd 7.3 b 7.5 b 9.2 bc 9.5 a
Pendimethalin 60WDG 4 5.5 f 5.5 e 6.8 b 5.7 c 9.1 c 9.7 a
Trifluralin 5G 2 9.3 a 9.6 ab 9.9 a 10.0 a 9.6 abc 9.2 a
Trifluralin 5G 4 9.5 a 9.7 a 9.9 a 9.7 a 9.9 a 9.7 a
(OH-2) Oxyfluorfen 3 9.6 a 9.3 abc 9.9 a 10.0 a 9.5 abc 7.5 b
+Pendimethalin (mulch)
(OH-2) Oxyfluorfen 3 6.9de 8.6 abcd 9.8 a 10.0 a 10.0 a 9.9 a
+Pendimethalin (no mulch)
1/ Means within columns, followed by the same letter, do not differ at the 5% level of significance (DMRT)

*Professor, Research Associate, Assistant Professor, and Professor of Horticulture, Department of Horticulture, The Pennsylvania State University, University Park, PA 16802.

Checkout the Conference Calendar Website at http://hortweb.cas.psu.edu/ohortex/greenindustrycal.html
If you have, programs that you would like added to the calendar, please forward the information to Jim Sellmer at jcs32@psu.edu. Review the information provided on the site and provide similar information for your program. Thanks!
Conference and Meeting Calendar

55th Pennsylvania Landscape & Nursery Conference
Date: February 9-10, 2000
Location: The Penn Stater Conference Center, University Park, PA
Contact: Jim Sellmer (814) 863-2250
Summary: This two-day conference brought to you by the Dept. of Horticulture, Penn State Cooperative Extension, & PA Landscape & Nursery Conference. The conference will have 4-current sessions along with general sessions and the topics will focus on the Landscape, Garden Center, Production Nursery, Business & Technology, and Plant Materials. New this year, there will be pre-conference workshops on Feb 8. These limited seating workshops will include Computer Assisted Design, Building a Web Page, Marketing, Recruiting and Retaining Employees, and Landscape Problems.

Information Update

Checkout the Conference Calendar Website at http://hortweb.cas.psu.edu/ohortex/greenindustrycal.html
If you have, programs that you would like added to the calendar, please forward the information to Jim Sellmer at jcs32@psu.edu. Review the information provided on the site and provide similar information for your program. Thanks!

Information provided by Rob Berghage and Jim Sellmer Penn State Department of Horticulture, Ornamental Horticulture Extension Specialist, 103 Tyson Building, University Park, PA 16802, (814) 863-2571
This publication is available in alternate media upon request

The Pennsylvania State University is committed to the policy that all persons shall have equal access to programs, facilities, admission, and employment without regard to personal characteristics not related to ability, performance, or qualifications as determined by University policy or by state or federal authorities. The Penn State University does not discriminate against any person because of age, ancestry, color, disability or handicap, national origin, race, religious creed, sex, sexual orientation, or veteran status. Direct all inquiries regarding the nondiscrimination policy to the Affirmative Action Director, The Pennsylvania State University, 201 Willard Building, University Park, PA16802-2801; tel. (814) 863-0471; TDD (814) 865-3175.

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