Influence of Sethoxydim Herbicide on the Performace of Capsicum spp.

Influence of sethoxydim herbicide on the performance of Capsicum spp.

by

Salah Shaikh (Biological Sciences and Public Health 2016)

Advisors: Albert Ayeni, and Carrie Mansue

Abstract:

Capsicum annuum (Jalapeno), Capsicum chinense (Habanero), and Capsicum frutescens (African

birdeye) are three pepper species becoming popular in America as ethnic crops. The objectives of this

experiment were to study the influence of sethoxydim (a grass herbicide) on the growth and performance

of these three pepper species and to determine if this herbicide may be safely used in them at rates that are

effective for weed control under greenhouse conditions. The results confirmed that sethoxydim is safe to

use in these pepper species and exhibits good smooth crabgrass (Digitaria sanguinalis) control.

Introduction

In this study 3 particular peppers were worked on: Capsicum annuum, Capsicum chinense, and capsicum

frutescens. These are some of the more high demand ethnic crops in America today. Capsicum annuum

species has several peppers like the cayenne, jalapeño, and the Peruvian purple peppers. The Capsicum

chinense include habanero, scotch bonnet, and the naga jolokia peppers. Finally, the Capsicum frutescens

include the tabasco, African birdeye peppers. These three particular species are some of the top ethnic

crops in today’s world (Ayeni). Capsicum annuum are native to Mexico and Central America but are

cultivated for food in many warmer regions of the world. Capsicum frutescens originated in Central or

South America. Now major portion Northern, Central and Western South America and southern regions

of Africa have begun to grow the plants. Capsicum Chinense originating from the Amazon into the

Caribbean and then spreading into Central and South America. These peppers have now been started to be

introduced in America and are now starting to be grown.

The reason for them being grown in America is that they have several key uses in human daily life. These

peppers can be used for culinary, medicinal, and ornamental uses. For culinary, cuisines that uses them is

the Ethiopian cuisine, where this species has been cultivated since the nineteenth century. It shows up

occasionally in Egyptian and Moroccan dishes too. The Tabasco pepper, is the same Tabasco pepper used

to make the world renowned Tabasco hot sauce. They are also used extensively as flavoring in several

cuisines including Indian, Thai, Korean and Chinese as well as in many Latin American and African

dishes. These peppers can be added to curries, pickles and chutneys. These pepper species also have many

uses in medicine. Capsaicin is the most-studied active ingredient in the plant can be useful for managing

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pain related to surgery and mouth sores due to chemotherapy and radiation therapy and is used by

alternative medicine practitioners as a remedy for a variety of conditions, such as upset stomach,

menstrual cramps, headaches, shingles, diarrhea, loss of appetite, stomach ulcers, poor digestion, sore

throat, itching, alcoholism, motion sickness, toothache, malaria, and yellow fever. Finally, these peppers

have ornamental uses for the eye catching display of the profusion of erect peppers growing in colorful

ripening patterns .Some cultivars grown specifically for their aesthetic value include the U.S. National

Arboretum's Black Pear and the Bolivian Rainbow. Ornamental varieties tend to have unusually colored

fruit and foliage with colors such as black and purple being notable.

In agriculture there are numerous plants that can be grown and numerous problems that arise from them.

One of the biggest problems in agriculture in weeds and weed management. Weeds can significantly

reduce crop yield and disrupt a plants growth. This can lead to economic problems for the grower. One of

the major weeds farmers have to deal with is the crabgrass weed. Crabgrass starts its growth usually in the

spring and grow until midsummer. This weed can adjust to both tropical and temperate conditions. It

grows in numerous countries and competes with many different crops and spreads very quickly. It is a

serious weed of cultivated fields, lawns, waste areas, and pastures. Once established, large crabgrass

tolerates both high temperatures and dry, compacted soils. Crabgrass is found in almost every turf and

landscape situation. It is prolific in lawns, golf courses, athletic fields, gardens, orchards, and waste

places. It thrives particularly well in lawn situations. This weed can cause numerous problems and can be

very detrimental to the farmer and to the crop the farmer wants to grow.

There are solutions to managing this prolific weed on the pepper plants. One of the techniques that can be

done to solve this problem is through hand weaning. The issue though is that it takes a long time, is very

tiring and can be very inefficient. Hence why there is a much more effective and easier way to manage

weeds. That solution is the use of herbicides. Herbicides are much more efficient and easier to manage

weeds than simply hand weaning. Crabgrass can be selectively controlled through the use of

postemergence herbicides. One particular post-emergent herbicide that can be used and is the main

herbicide in this study is Sethoxydim. The trade name for Sethoxydim is Poast. This herbicide is a

selective postemergence herbicide that is used to control grasses in broadleaf (dicot) plants such as pepper

and does so in a systemic manner. Sethoxydim (Poast) can be applied to control most annual and

perennial grasses and on grass crops such as peppers and corns. Sethoxydim is known to have good

selectivity on peppers It kills grass leaves but not broadleaf weeds. Sethoxydim enter weed through its

foliage and translocates throughout the plant. It can slow or stop growth. The weed will usually have

foliage redding and leaf tip burn (Ayeni) Its mode of action is Mode of Action is that they are ACCase

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Inhibitors (lipid biosynthesis inhibitors) . It can slow or stop growth. The weed will usually have foliage

redding and leaf tip burn.

These peppers are of vital importance to our daily lives and must be able to prosper and grow. However,

if the crabgrass weed can in fact take over, it will reduce the yield of these plants and thus puts the grower

in a difficult economic spot. It will also be detrimental to us as humans due to the many versatile uses

these 3 pepper species have on our daily lives. Peppers are a warm-season crop that need a long growing

season. Peppers nearly all transplanted, which can give the crop some advantage over weeds. However,

pepper transplants are slow to establish and compete poorly with weeds, such as crabgrass which can

reduce pepper yields by competing for light, water, and nutrients as well as delaying maturity.

With all of this in mind, the main objective of this experiment is to see how 3 pepper species (Capsicum

annuum, Capsicum chinense, and Capsicum frutescence) respond to Sethoxydim treatment at various

concentrations (control, recommended rate, and double the recommended rate) and see if any of those

treatments affect the plant itself, and fruit yield. Sethoxydim is favorable to pepper in terms of killing

weeds, but to which specific peppers is the question being dealt with in this study. Another objective is to

see if sethoxydim kills the weed crabgrass just to ensure that the sethoxydim is working. Sethoxydim is

known to work on crabgrass. The herbicide efficacy on crabgrass can be done to confirm that the

herbicide works as expected. The hypothesis that is being tested will be how the Capsicum Species will

respond differently to different sethoxydim treatments and if the sethoxydim treatments will successfully

kill off the crabgrass. The results that are expected to be seen is that sethoxydim will kill off the weeds

and that sethoxydim will not disturb fruit yields and can be safe to use, just as herbicidal companies are

advertising.

Materials and Methods

Growing the seedlings of the plants began on July 10th 2014. The plants were watered regularly

throughout the study period in the greenhouse. On September 5th 2014, the seedlings were transferred

into biodegradable pots where they were filled up with greenhouse soil to the top of the pot. These unique

pots allowed for the isolation the plant species with the crabgrass on the same pot so it can be easier to

observe the effects of Sethoxydim on both. . One week later, the crabgrass weed seeds were put on the

side of the pot that was unoccupied. They along with the plant were being watered everyday. Each plant

was given a label to denominate the plant species, the concentration of Sethoxydim it was getting and the

replication number. For example, F0I identifies it as Capsicum frutescence with 0 concentration and is in

replication 1. Once they were transferred and labeled, a randomized block was done with 4 replications

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for a total of 36 plants. The plants were still being watered every other day. 2 weeks after putting the

weeds in the pots the plants and weeds were applied Sethoxydim except for the ones labeled 0

concentration. The herbicide machine sprayed a certain amount of sethoxydim depending on the

concentrations the plant was getting based on the label it got. The following amount of treatments were 1

pt/AA (recommended rate) and 2 pt/AA (double the recommended rate). There was 70 ml per treatment

mixture to spray 20 gallons/area of sethoxydim.

Once the herbicidal treatment was done, that officially marked the first day of observations. Observations

were to be taken every week for 8 weeks. The following things that were being observed are as follows:

Plant height, number of leaves, number of branches, number of flower buds, number of flowers, number

of fruits, crabgrass rate (0 = no kill; 5= total kill)/ weed development (for the last week of observations,

the weed height was taken), leaf color, plant injury (could be on the leaves, flower buds, fruits, etc.). For

plant height, a meter stick was used. In order to avoid the yellowing of leaves, 20-20-20 NPK fertilizer

was used once every 4 weeks starting on 9/30/2014. 8 weeks after development of the plant and crabgrass

weed, the final observations were taken down. Then, the weeds 8 weeks into development from each of

the pots were cut near the root in order to measure their fresh weights. A scale (in grams) was used to

measure them. Once the weeds were measured, they were put in one pamphlet, which was labeled for the

pot they were on. Once all the weeds from the 36 pots were measured, they were taken to a dryer that was

at 55 degrees Celsius. The pamphlets were left there for 4 days and then taken out again. This is to now

measure their dry weights. The same scale was used and each of the 36 measurements were taken down.

The data was handled by making simple comparisons and will be subjected to future statistical analysis.

Key Dates:

7/10/2014: Pepper seed was planted to raise seedlings

9/5/2014: Seedlings were transplanted into pots

9/12/2014: Crabgrass seed was planted

9/26/2014: Applied sethoxydim herbicide

9/30/2014: Applied 20-20-20 NPK General Purpose fertilizer

10/28/2014: Applied 2nd application of 20-20-20 NPK fertilizer

11/21/2014: Cut off the crabgrass weeds and took fresh weights

11/25/2014: Took dry weights; dried at 55 degrees Celsius

Fresh Weights: done on 11/21/2014Dry Weights: done on 11/25/2014 at 55 degrees celsius

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Table 1.1:

Plant Sethoxydim rate(pt/AA)

Fresh wt. (g) Dry wt. (g)

Jalapeno 0 29.6 4.6

1 1.5 0.3

2 0.3 0.1

Habanero 0 16.6 2.7

1 0.5 0.1

2 0.2 0.1

African Birdseye 0 19.9 3.0

1 1.7 0.3

2 0.4 0.1

Capsicum annuum:

Week 0 left; week 4 right; week 8 bottom

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Capsicum Chinense:

Week 0 left; week 4 right; week 8 bottom

6

Capsicum frutescens:

Week 0 left; week 4 right; week 8 bottom

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Discussion:

One result that was shown in this study was that the height, leaves, branches, and fruit yield all increased

in all the plants weekly regardless of the amount of concentration of sethoxydim it was given. Some

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plants with a 2x had more fruit yield than a 1x and some 1x had more fruit yield than a control. For

example, in Figure 5.1, Jalapenos with 1 pt/AA had more fruit yield in week 8 than the Jalapeno’s plant

with no sethoxydim application.. There was a study done by the Northeastern Weed Science Society that

showed that there was no phytotoxicity of pepper was observed with sethoxydim and that Sethoxydim did

not result in injury or reduction of plant yield compared to the control. (Orzolek et.al, 1986). Figures 1.1,

2.1, and 3.1 all show the upward trend during the weeks for height, leaves, and branches respectively.

Those traits were not affected by the sethoxydim treatment/

Another result was the weed rating that initially went down, but then the majority began to grow back up.

For instance, in figure 6.1, weed rating through week 4 was around 4 for plants with 2pt/AA and weed

rating was around 3 for 1 pt/AA. However, in week 8, weed rating lowered to about 3.5 for 2pt/AA and

weed rating around 2-2.5 for 1 pt/AA. That same Northeastern study also showed that sethoxydim did in

fact have excellent grass control in pepper. (Orzolek et.al, 1986). However in that study herbicide

application was done at intervals, while in this experiment it was only put once.

There are 2 major implication of this result, this can lead to an increase production of the 3 peppers and

that the peppers can be safely grown in greenhouse conditions. For the increase production of peppers.

One study showed that there is a strong demand and interest for ethnic produce in East Coast. (Ayeni

et.al, 2008). Producers can concentrate effort in producing ethnic vegetables and fresh produce and

making newer products available in the local and regional markers (Ayeni et.al, 2008). The frequency of

purchase of ethnic products for Chinese they shopped on average 55% more frequently and spent $98 on

average monthly ethnic produce expenditures; $91 for Asian Indian; $79 for Mexican and $77 for Puerto

Rican(Ayeni et.al, 2008). About 46-56% of the purchasers in each group were “more willing” to purchase

ethnic produce (Ayeni et.al, 2008). A large percentage of non-purchasers were “more willing” to purchase

ethnic produce that were sold in ethnic outlets (40%) or grown on local farms (42%). (Ayeni et.al, 2008).

35% of non-purchasers indicated they would be “more willing” to buy ethnic produce in the future.

(Ayeni et.al, 2008). These results can help show that the local producers who are struggling to compete in

national markets can benefit by concentrating their efforts in the production of ethnic vegetables such as

the 3 Capsicum spp. This could help the farmer economically and can benefit the population with the

culinary, medicinal and ornamental uses. The 3 pepper species can help in creating a growing market

demand for ethnic crops thus increasing their yield here in the U.S.

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For the greenhouse, the 3 pepper species can be grown in greenhouse conditions using sethoxydim as the

herbicide. However, greenhouse conditions differ much from field conditions so these results have to be

confirmed in field conditions.

Based on all of these aspects of the results, the hypothesis can be confirmed that sethoxydim is a safe

herbicide that will not affect the pepper yields and can kill off the crabgrass weeds when used effectively.

Conclusion and Recommendations

From this study it is shown that sethoxydim is a safe herbicide to use on the 3 Capsicum spp. and that the

hypothesis can be confirmed. Sethoxydim is also very good on weed control, but be wary of any weed

regrowth that could occur. This experiment should be tested in field conditions to confirm the results.

Finally, the Capsicum frutescens should be hand weaned periodically to increase fruit yield and to grow

fruit at an earlier time.

Acknowledgement:

Professor Albert Ayeni for giving the resources to do the experiment and Carrie Mansue for putting the

herbicide and general guidance. Both are greatly appreciated for their efforts.

Literature Cited:

1. Smith, R.F. 2011. Integrated Weed Management. Retrieved December 11, 2014, from http://www.ipm.ucdavis.edu/PMG/r604700111.html

2. Anonymous. 2014. Large Crabgrass - Weed Management (Penn State Extension). Retrieved December 11, 2014, from http://extension.psu.edu/pests/weeds/weed-id/large-crabgrass

3. Anonymous. 2011. Biology and Management of Crabgrass. (n.d.). Retrieved December 11, 2014, from https://extension.umass.edu/turf/fact-sheets/biology-and-management-crabgrass

4. Anonymous. 2008. Capsicum. Retrieved December 11, 2014, from http://www.cancer.org/treatment/treatmentsandsideeffects/complementaryandalternativemedicine/herbsvitaminsandminerals/capsicum

5. Orzolek, M. D., Ferretti, P. A., & Reitz, W. L. (1986). The effect of postemergence grass herbicides on the weed population in and yield of tomato and pepper. Proceedings of the ...Annual Meeting - Northeastern Weed Science Society., , 176-178. Retrieved from http://search.proquest.com/docview/49783978?accountid=13626

6. Govindasamy, R., VanVranken, R., Sciarappa, W., Ayeni, A., Puduri, V. S., Pappas, K., . . . McAvoy, G. (2008). Ethnic crop opportunities for growers on the east coast: A demand assessment. Proceedings of the ...Annual Meeting of the Florida State Horticultural Society., , 36-49. Retrieved from http://search.proquest.com/docview/46346967?accountid=13626

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