SWSS Weed Contest

Southern Weed Science Contest Announcement
August 7, 2024

Virginia Tech Kentland Farm, Blacksburg, VA
Primary contacts: Shawn Askew – saskew@vt.edu
Michael Flessner – flessner@vt.edu
August 7, 2024





The purpose of the Southern Weed Contest is to provide an educational experience from which undergraduate and graduate students in Southern Universities can broaden their applied skills in Weed Science. The contest provides an opportunity for Weed Science students be exposed to weed scientists from other universities and industry, apply what they have learned using a contest to measure their capabilities, as well as to socialize. It is hopeful that the contest will increase the visibility of Weed Science and intensify the interest level of those participating in the discipline of Weed Science.


Any undergraduate or graduate student currently enrolled and pursuing a B.S., M.S., or Ph.D. degree is eligible to participate. Each graduate team will consist of three or four members, composed of (a) graduate, (b) undergraduate, or (c) a combination of graduate and undergraduate students. If a university does not have sufficient students for a team, up to two students may enter as individuals. All students will compete using the same contest material. A team may also bring two alternates. Alternate scores will only count toward individual awards. Team scores will be determined from averaging the individual scores from each team member; unless a three-person team is entered. Then the three highest individuals will be averaged. A maximum of two coaches per team can attend the contest. Students will be allowed to participate in the contest five times as a team member or alternate; however, the student can only participate as a team member three times. Undergraduate participation will not count against the five-time rule.

All teams must enter the contest by May 1, 2024. Names of team members and alternates must be provided by July 1, 2024 to contacts above.

Click here to sign up for the contest.


TEAM-The highest average team score from all events will determine the overall contest winner. A traveling “Broken Hoe” trophy will be presented to the overall winner and will rotate yearly. The first place team will receive a check for $500 and each member and coach will receive an engraved plaque. The second and third place teams will receive checks of $300 and $200, respectively. Each will also receive an engraved plaque as described above.

INDIVIDUAL-The highest combined score from all events, except team sprayer calibration, will determine the overall-winning individual. The Top 5 awarded a plaque and the top 10 individuals will be recognized. The winning individual will receive a check for $400. Individuals finishing second, third, fourth, and fifth will receive checks from $250, $100, $75, and $50, respectively. The high individual in Weed Identification, Crop Response to Herbicides, Sprayer Calibration Problem Set, and Crop/Weed Situation and Recommendations will be recognized and awarded a plaque. If at least four undergraduate students participate in the contest, the top three individual scores will be recognized with first, second, and third place plaques and checks for $200, $100, and $50, respectively.


The contest will consist of four major events plus a mystery event. Inclement weather may delay the contest; however, it will continue as soon as conditions permit.

While contestants are briefed on contest details. Coaches will be taken to the contest site to review all aspects of the contest. Coaches will review the six phases of the contest: weed identification, herbicide identification, sprayer and written calibration, crop/weed situation and recommendations, and mystery event. The coaches will then be taken to a neutral site. No contact, electronic or otherwise, with contestants will be allowed until all events have been completed. A committee meeting will also be conducted, if needed, either the day before the contest or on the day of the contest.

  1. Weed Identification (100 points)

From the contest weed identification list of 100 weeds and weed seeds/tubers, the host will pick a total of 50 weeds and/or weed seeds to be identified. Plants could either be grown in a field weed nursery or pots or presented in digital picture form (must be of good quality and clarity) and may be in any stage of growth or development within reason. A complete weed identification list is provided with the correct spelling of each species (Table 1). Students will be responsible for the correct common and scientific name and spelling (WSSA Composite List of Weeds). All answers must be printed (no cursive allowed) and must be legible to be awarded credit for correct answers. Undergraduate students will only use the common names. The fall preceding the contest the host should evaluate its weed seed supply and obtain additional seeds/tubers if needed so that an excellent representation of the weed species can be selected for identification. It is important to utilize as many plant species as possible. The plants will be grown in sufficient numbers so that adequate samples are available so that 30 to 70 contestants can have specimens for identification. The contestants will be allowed ample time to identify each specimen. The percentage of samples will range from 50 to 80% weeds and from 50 to 20% seeds. Uncontaminated samples are essential for effective identification. Pure samples are essential. The contestant’s score will be figured as follows: 2 points for each correctly identified species (1 point for common name and 1 point for scientific name with 0.5 points for genus and 0.5 points for species) x 50 = 100 points. If names are not spelled correctly or capitalized correctly, they are wrong. Likewise, answers must be in the correct column. Teams will not be supplied weed seed for study, but rather rely on their own training resources.

However, teams are encouraged to expand/improve their training resources through contacts with other weed scientists. This approach may better reflect individual and team preparation for the contest.

  1. Calibration (100 points)

This event consists of two sections: an individual written test worth 50 points and a team sprayer calibration event worth 50 points.

The individual written test will cover problems and factual information about sprayer and seed treatment calibration of all types; the written portion will be scored as an individual and team event (50 points per person). The host should take particular care to insure all banded application and skip-row calibration problems are stated clearly. Individual team members and alternates will be given a maximum of 1 hour to complete the written exam. The host will provide calculators and students will not be allowed to use their own. The three or four individual team member scores will be added and divided by the number of individuals on the team to give the number of points out of 50 for the team score.

In the team section, the host will provide a hands-on calibration activity that focuses on team, rather than individual performance. Students should have practical calibration knowledge for air blast sprayers, tractor sprayers, backpack sprayers, granular applicators, greenhouse spray chambers, etc. Differences in time for the competition will count no more than 40% of the overall score. Accuracy of calibration is critical.

To determine final team score for the calibration event, the number of points scored out of 50 obtained in the team event will be added to the average score of the three or four high team members from the individual calibration problems for a maximum possible of 100 points.

Reference material includes various Weed Science textbooks, Herbicide Handbook, and various unit conversions.

  1. Herbicide Identification (100 points)

This is an area of extreme difficulty for the students. Thus, the host must have available a sprinkler irrigation system so that residual herbicides may be activated and weeds and crops maintained in an active growth stage for postemergence treatments. A list of possible crops and herbicides with rate and method of application are provided in Table 2. The test must contain at least 6 crops and 6 weeds and will be planted and treated with a wide range of preemergence and postemergence herbicides from the list. Each herbicide plot will contain a 1X rate of the unknown herbicide. It is suggested that the test be planted 4 to 5 weeks prior to the contest, with postemergence herbicides being applied 10 to 14 days prior to the contest. Each contestant will be required to identify the unknown herbicides by the WSSA group number and common name by observation of crop and weed responses. Both names and group number will be given equal credit; in other words missing common name or group number will behalfright.

There should be from 10 to 15 plots. Herbicide plots may be duplicated and check plots can be utilized. It would be of great benefit to the students if they could be led back through the plots following the event. Students will not be allowed to pull any portion of the plants in the plots. If plants are pulled, the student will lose the points for that plot.

  1. Crop/weed Situation and Recommendations (100 points)

Contestants will be required within 15 minutes to determine and evaluate a crop/weed situation and recommend the most effective legal remedy to the problem. Each contestant will have two field problems to solve. Recommendations must comply with the label of each herbicide recommended. Students should give consideration to such factors as stage of growth, crop tolerance, climatological factors, agricultural spraying procedures, weed control, economics, and impact upon the environment. The host will determine the best answer considering all alternatives for a situation, although several possible answers may be correct. The latest Federal (Section 3) or State (Section 24C) labels of the product constitutes legal control. The event will be conducted as a “role-play” situation and the potential problem will be in one of the crops on the problem-solving sheet. Also, the crop/weed situation will involve only the listed herbicides and weeds on the predetermined problem-solving sheet. The contestant will be asked to assume the role of a chemical company representative, state extension specialist, or independent crop consultant when dealing with the farmer and scored as follows:

5 points – proper approach/greeting to farmer

20 points – understanding and solving problem

12.5 points – recommendations for this year’s crop

12.5 points – recommendations for next year’s crop


Each team will be divided at random into two groups in order to handle one of two different problem situations. Following completion of the first problem, the groups will switch problems and repeat the procedure. Each participant will evaluate the same two problems. Alternates and other individuals will be equally divided between the two groups. The assigned judge and farmer will independently score each participant from a predetermined scoring sheet with assigned points for each statement, compare scores, and adjust if necessary. Prior to the contest, judges and farmers will be tested to ensure that the scorers will give equivalent scores within each individual field problem. Each field problem will be worth 50 points and to obtain the participants score, the two scores will be added for a maximum of 100 points.

  1. Mystery Event (15 points)

This team or individual event will be an agronomic related problem and the contestants will not be advised of the area to study prior to the contest. The mystery event will count toward the team score and individual scores.


Overall team ranking of each respective school should be provided to the team coach the night of the banquet following the event. Individual score sheets including their respective ranking against all other competitors should be distributed back to the contestants or their coach at the end of the banquet. An answer key should also be distributed to the team coach.

Scores should be tabulated using a scoring format as listed in the examples below. Each phase of the contest will be scored equally (100 pts. each) except for the mystery event (15 pts) for a total of 415 points per team.

Examples are:

A. All teams with four individuals.


Field Problem          Calibration

Super University ID Crop/Weed Response 1 2 Avg. Team Ind. Myst. Score Ind. Team Placing
John Doe 86 60 25 19 44 45 5 240 9
Bill Smith 80 65 47 31 78 35 5 263 5
Jane Doe 95 75 35 25 60 45 0 275 1
Roy James 63 50 43 43 86 45 3 247 7















Team Avg. Team Total 81.0




62.5 67 40 42.5 3.25  




Pat Ray 80 60 31 201 51 45 5 241 8
Jim Jones 65 45 27 18 45 50 0 205 20


B. Mixed three and four individual teams (if teams with three individuals attend).


Field Problem          Calibration

Super University ID Crop/Weed Response 1 2 Avg. Team Ind. Myst. Score Ind. Team Placing
John Doe 240 9
Bill Smith 80 65 47 31 78 35 5 263 5
Jane Doe 95 75 35 25 60 45 0 275 1
Roy James 63 50 43 43 86 45 3 247 7
Total 238.0 190.0 224 125 8
Team Avg.








































Pat Ray 80 60 31 20 51 45 5 241 8
Jim Jones 65 45 27 18 45 50 0 205 20

Alternates and low individuals of four member teams will not be scored as part of a team, but can win individual prizes.

Contest Committee:

All coaches and individuals within academia, research, and industry, as well as potential contest hosts are invited to serve on the committee. On the morning of the contest, prior to contestants entering the events, individuals from the host location and all committee members will review each event and last minute corrections will be made and be the authority for all questions relating to the contest. If questions arise that cannot be resolved through interpretation of the standing rules or cannot be resolved through communication with the committee chairman or members of the committee, the contest host has the authority to make the final decision in the best interest of the contest.


Each university will provide its own transportation to and from the contest and cover all expenses incurred during travel. The host will provide meals the evening before and the day of the contest. The weed contest committee will provide the prize money and the plaques.


The Southern Weed Contest will be held at any facility within the Southern Weed Science Region with the capability of providing all the designated events.


All coaches are charged with ensuring that teams abide by rules of the contest, and that no team gains an unfair advantage. This includes, but is not limited to, cheating. Cheating is defined as a dishonest violation of rules as determined by the coaches attending the contest. A committee made up of all coaches attending the contest will deal with acts related to cheating. A team and/or individual that does not abide by the rules of the contest will be disqualified and will automatically receive last place at the contest. Teams are not allowed to visit contest site 30 days prior to contest without permission of host. All contestants’ cell phones, iPad’s, or computers will be collected by team coaches and bagged by individual name when arriving at the contest site on the morning of the event.


  Common name Genus Species
1 velvetleaf Abutilon theophrasti
2 hophornbeam copperleaf Acalypha ostryifolia
3 tree-of-heaven Ailanthus altissima
4 alligatorweed Alternanthera philoxeroides
5 Palmer amaranth Amaranthus palmeri
6 redroot pigweed Amaranthus retroflexus
7 spiny amaranth Amaranthus spinosus
8 waterhemp Amaranthus tuberculatus
9 common ragweed Ambrosia artemisiifolia
10 giant ragweed Ambrosia trifida
11 purple ammannia Ammannia robusta
12 broomsedge Andropogon virginicus
13 jointhead arthraxon Arthraxon hispidus
14 trumpet creeper Campsis radicans
15 musk thistle Carduus nutans
16 southern sandbur Cenchrus echinatus
17 common lambsquarters Chenopodium album
18 bull thistle Cirsium vulgare
19 Benghal dayflower Commelina benghalensis
20 spreading dayflower Commelina diffusa
21 field bindweed Convolvulus arvensis
22 smellmelon Cucumis melo
23 bermudagrass Cynodon dactylon
24 horseweed Erigeron canadensis
25 spotted spurge Euphorbia maculata
26 showy crotalaria Crotalaria spectabilis
27 tropic croton Croton glandulosus var. septentrionalis
28 bermudagrass Cynodon dactylon
29 yellow nutsedge Cyperus esculentus
30 purple nutsedge Cyperus rotundus
31 rice flatsedge Cyperus iria
32 crowfootgrass Dactyloctenium aegyptium
33 jimsonweed Datura stramonium
34 Florida beggarweed Desmodium tortuosum
35 smooth crabgrass Digitaria ischaemum
36 large crabgrass Digitaria sanguinalis
37 Virginia buttonweed Diodia virginiana
38 Amazon sprangletop Diplachne panicoides
39 bearded sprangletop Diplachne fusca var. fascicularis
40 barnyardgrass Echinochloa crus-galli
41 eclipta Eclipta prostrata
42 autumn olive Elaeagnus umbellata
43 goosegrass Eleusine indica
44 southwestern cupgrass Eriochloa acuminata
45 wild poinsettia Euphorbia heterophylla
46 Carolina geranium Geranium carolinianum
47 ground ivy Glechoma hederacea
48 common sunflower Helianthus annuus
49 hydrilla Hydrilla verticillata
50 cogongrass Imperata cylindrica
51 red morningglory Ipomoea coccinea
52 ivyleaf morningglory Ipomoea hederacea
53 pitted morningglory Ipomoea lacunosa
54 bigroot morningglory Ipomoea pandurata
55 tall morningglory Ipomoea purpurea
56 palmleaf morningglory Ipomoea wrightii
57 smallflower morningglory Jacquemontia tamnifolia
58 false green kyllinga Kyllinga gracillima
59 henbit Lamium amplexicaule
60 tall fescue Lolium arundinaceum
61 Italian ryegrass Lolium perenne ssp. multiflorum
62 Japanese stiltgrass Microstegium vimineum
63 carpetweed Mollugo verticillata
64 cutleaf evening primrose Oenothera laciniata
65 red rice Oryza sativa
66 yellow woodsorrel Oxalis stricta
67 fall panicum Panicum dichotomiflorum
68 torpedo grass Panicum repens
69 dallisgrass Paspalum dilatatum
70 Pennsylvania smartweed Persicaria pensylvanica
71 ladysthumb Persicaria maculosa
72 cutleaf groundcherry Physalis angulata
73 clammy groundcherry Physalis heterophylla
74 buckhorn plantain Plantago lanceolata
75 annual bluegrass Poa annua
76 prostrate knotweed Polygonum aviculare
77 common purslane Portulaca oleracea
78 kudzu Pueraria montana
79 wild radish Raphanus raphanistrum
80 Florida pusley Richardia scabra
81 multiflora rose Rosa multiflora
82 curly dock Rumex crispus
83 sicklepod Senna obtusifolia
84 coffee senna Senna occidentalis
85 hemp sesbania Sesbania herbacea
86 giant foxtail Setaria faberi
87 yellow foxtail Setaria pumila
88 green foxtail Setaria viridis
89 arrowleaf sida Sida rhombifolia
90 prickly sida Sida spinosa
91 Carolina horsenettle Solanum carolinense
92 eastern black nightshade Solanum ptychanthum
93 lawn burweed Soliva sessilis
94 johnsongrass Sorghum halepense
95 common chickweed Stellaria media
96 dandelion Taraxacum officinale
97 puncturevine Tribulus terrestris
98 broadleaf signalgrass Urochloa platyphylla
99 Texas millet Urochloa texana
100 common cocklebur Xanthium strumarium

*    Bold — plants only



        Crops*                                                                   __Weeds       

1. cotton 6. alfalfa 1. broadleaf signalgrass 7. Palmer amaranth
2. field corn 7. soybean 2. ivyleaf morningglory 8. pitted morningglory
3. grain sorghum 8. sunflower 3. fall panicum 9. prickly sida
4. pumpkin 9. wheat


4. hemp sesbania 10. seedling johnsongrass
5. rice 10. canola  canola 5. large crabgrass 11. velvetleaf
6. yellow nutsedge 12. sicklepod

*At least 6 crops and 6 weeds must be included

Common name Trade name Herbicide family Site of action (SOA) Group # (SOA) Application timing Rate and adjuvant
clethodim Select Max cyclohexanedione ACCase inhibitor 1 POST 0.091 lb ai/a + NIS 0.25%
pinoxaden Axial XL phenylpyrazoline ACCase inhibitor 1 POST 0.054 lb ai/a + NIS 0.25%
cloransulam FirstRate triazolopyrimidine ALS inhibitor 2 PRE 0.032 lb ai/a + NIS 0.25%
imazethapyr Pursuit imidazolinone ALS inhibitor 2 PRE 0.063 lb ai/a + NIS 0.25%
chlorimuron Classic sulfonylurea ALS inhibitor 2 POST 0.008 lb ai/a + NIS 0.25%
trifloxysulfuron Envoke sulfonylurea ALS inhibitor 2 POST 0.007 lb ai/a + NIS 0.25%
nicosulfuron Accent Q sulfonylurea ALS inhibitor 2 POST 0.031 lb ai/a + COC 1%
pendimethalin Prowl H2O dinitroaniline Microtubule assembly inhibitor 3 PRE 1.43 lb ai/a
2,4-D 2,4-D LV4E phenoxy-carboxylic-acid Synthetic Auxin 4 POST 0.5 lb ae/a
dicamba Clarity benzoate Synthetic Auxin 4 POST 0.25 lb ae/a + NIS 0.25%
quinclorac Facet L quinoline carboxylic acid Synthetic Auxin 4 POST 0.375 lb ae/a + MSO 1.5 pt/a
atrazine AAtrex 4L triazine Photosystem II Inhibitor 5 PRE 2.0 lb ai/a
metribuzin Metribuzin 75DF triazinone Photosystem II inhibitor 5 PRE 0.375 lb ai/a
bentazon Basagran 5L benzothiadiazinone Photosystem II inhibitor 6 POST 1.0 lb ai/a + COC 1%
bromoxynil Buctril nitrile Photosystem II inhibitor 6 POST 0.375 lb ai/a + NIS 0.25%
linuron Linex 4L urea Photosystem II inhibitor 5 PRE 0.75 lb ai/a
fluometuron Cotoran 4L urea Photosystem II inhibitor 5 PRE 1.0 lb ai/a
glyphosate Roundup PowerMAX 3 glycine EPSP Synthase Inhibitor 9 POST 1.13 lb ae/a + AMS 8.5 lb/100 gal
glufosinate Liberty 280SL phosphinic acid Glutamine Synthetase Inhibitor 10 POST 0.402 lb ai/a + AMS 3 lb/A
clomazone Command 3ME isoxazolidinone DOXP synthase inhibitor 13 PRE 0.56 lb ai/a
flumioxazin Valor EZ N-phenyl imide PPO inhibitor 14 PRE 0.078 lb ai/a
fomesafen Reflex diphenyl ether PPO inhibitor 14 POST 0.25 lb ai/a + NIS 0.25%
saflufenacil Sharpen N-phenyl imide PPO inhibitor 14 POST 0.022 lb ai/a + MSO 1% + AMS 8.5 lb/100gal
pyroxasulfone Zidua SC isoxazoline Very long-chain fatty acid synthesis inhibitor 15 PRE 0.098 lb ai/a
S-metolachlor Dual II Magnum α-chloroacetamide Very long-chain fatty acid synthesis inhibitor 15 PRE 1.27 lb ai/a
paraquat Gramoxone pyridinium Photosystem I electron diverter 22 POST 0.5 lb ai/a + NIS 0.25%
mesotrione Callisto triketone HPPD inhibitor 27 PRE 0.094 lb ai/a + COC 1%
topramezone Impact pyrazole HPPD inhibitor 27 PRE 0.022 lb ai/a + MSO 0.5%

COC = crop oil concentrate; NIS = nonionic surfactant; MSO = methylated seed oil. % are on a vol/vol basis.



Potential Crops (6):

Cotton, field corn, grain sorghum, soybean, tall fescue (forage and turf), non-crop (rights-of-way, etc.)


Any weed from the weed identification list above.


Any herbicide labeled in the crops listed above.


The ‘farmer’ and a judge will independently score each contestant from predetermined scoring sheet.


Each contestant will be assuming the role of a chemical company representative, independent crop consultant, or state extension specialist.