Name

I EXPECT BRIEF, CLEAR, NEATLY WRITTEN, COMPLETE SENTENCE ANSWERS TO THE FOLLOWING QUESTIONS. Read the entire exam, note the points per question, and note the number of questions on the exam prior to beginning; this will help you manage your time. Then carefully read each question and answer only what is asked.

The following situation applies to all of question 1: You are a BLM land manager in New Mexico and you recently observed an infestation of an unusual plant species. You send a specimen to NMSU and the Weed Specialist determines that the plant is an exotic, introduced creeping perennial plant species from either Europe or Asia.

15 points 1. a. Is this plant a weed? why? What characteristics must this plant possess if it is a weed (ie how would you convince your superiors that this plant may be a threat/problem on BLM land).

Consider each of the following scenarios and describe the best management practice(s) for the weed. What are the positive and negative consequences of your choice in each case?

5 points b. This is the first observation of this plant species in the United States. The plant is on the Federal Noxious Weed list and the infestation is small and isolated.

5 points c. This is not the first observation of this plant species in the United States. The number of states where the plant has been observed is limited at this time. The plant is on the Federal Noxious Weed list; however, control efforts have never been initiated. The infestation has spread beyond a small, isolated patch and occurs in a remote wilderness recreation area.

5 points d. This plant species is a major problem in neighboring states and appears on noxious weed lists in the majority of the Western states. The infestation is fairly small and occurs in an isolated area but the plant is closely related to an endangered plant species.

5 points 2. a. What is classical biological control? List the steps involved from identification of a weed through implementation of the release of a classical biological control agent. 5 points b. What types of ecological systems have recorded the most successes with classical biological control, why?

5 points c. What is the cost/benefit ratio for successful implementation of classical biological control - explain. 30 points (5 points/answer) 3. You have observed the following weed species in your fields: Palmer amaranth (summer annual) - heavy infestation throughout khakiweed (creeping perennial) - moderate infestation South end of field yellow nutsedge (creeping perennial) - moderate infestation throughout Johnsongrass (creeping perennial) - light infestation throughout London rocket (winter annual) - moderate infestation throughout musk thistle (biennial) - light infestation North end of field dandelion (simple perennial) - moderate infestation North and South ends of field barnyardgrass (summer annual) - heavy infestation throughout downy brome (winter annual grass) - moderate infestation throughout tall mornningglory (summer annual) - light infestation throughout bermudagrass (creeping perennial) - light infestation South end of field

a. You are considering building a home and establishing hybrid bermudagrass turf on one end of the fields. You like the landscape potential on the West end and the South end of the property. Which would be better suited for turf? Why?

b. You are considering changing from conventional tillage to no-tillage management in the North fields. What were the major weed problems in this field under conventional tillage? Why? c. If you switch to no-till in the North field, what will the weed problems be? Why?

d. Is tillage effective for managing creeping perennial weeds? Explain.

e. You will be establishing an onion crop on the east fields in October. What weeds will emerge after establishment of this crop in the fall of the year.

f. October seeded onions are generally harvested during June of the following year. If you manage the weeds during the fall and winter, will there be any weed problems during harvest? Why (if you say there are problems - what will they be) or why not?

10 points 4. Briefly define the following terms.

allelopathy

noxious weed

seed bank

primary tillage

cultural control

5 points 5. You planted dill 10 days ago using conventional tillage and seedbed preparation. The field was irrigated immediately after planting. The dill has not started to emerge but a flush of weeds, primarily broadleaf weeds, has emerged. What can you do to manage these weeds?

10 points (5 points/answer) 6. You are managing two adjacent fields; one is planted with field corn and the other cotton. The major weed problem in both fields is spurred anoda (a summer annual broadleaf weed). (assume equal economic value of both crops) a. The density of spurred anoda in both fields is about 1 plant per 3 feet of row. Which crop is being affected more by the spurred anoda? Why (I am looking for two points - at least).

b. The fields were planted at the same time. Two weeks after crop emergence, spurred anoda begins to emerge in both of the fields. You only have time this week to cultivate one of the crops; which crop would you cultivate and why.

Name

REMEMBER, I EXPECT BRIEF, LEGIBLE, COMPLETE SENTENCES ANSWERING THE FOLLOWING QUESTIONS. Also, a word of caution: do not provide extra information unless you are sure of the answer. I will count off points for incorrect, extra information.

15 points 1. Definitions: Briefly define the following terms.

Herbicide resistance -

photodegradation -

mode of action -

transfer process -

site of action-

degradation process -

absorption -

15 points 2. Two broadleaf weed species, spurred anoda and Palmer amaranth, are growing together in two adjacent fields. The North field has a clay loam soil with 2% organic matter and the South field has a loamy sand soil with 1% organic matter. A herbicide was applied preplant incorporated at the same rate to both fields on the same day prior to planting cotton. In the North field (clay loam soil), only the spurred anoda is showing injury symptoms while in the South field (loamy sand soil), both weed species are injured and most of the spurred anoda is dead. The injury symptoms include bleaching of the plant tissue with some reddening of the tissue and necrosis.

2. a. What is the mode of action of the herbicide? Provide an example (common name) of a herbicide with this mode of action.

2. b. Why is the Palmer amaranth showing herbicide injury symptoms only in the South field? What process is responsible for the difference in plant damage observed between the two fields? Discuss the impact of this process on the fate of herbicides in soil.

2. c. Describe the major problems encountered with the use of the herbicides with this mode of action.

15 points 3. a. Draw, on the figure below, the response of two plants growing in a sandy loam soil low in organic matter to increasing rates of a foliar applied herbicide. Plant A is resistant to the herbicide while Plant B is susceptible to the herbicide. Be sure to label which line is Plant A and which line is Plant B.

100 % growth

inhibition

50

herbicide rate of application

3. b. Briefly discuss the physical factors that may influence the difference in response between the two plants to the herbicide.

3. c. Briefly discuss the biological factors that may influence the difference in response between the two plants to the herbicide.

4. Answer the following questions with words or with the letter of the appropriate chemical. 15 points

A. 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid

B. (2,4-dichlorophenoxy)acetic acid

C. 3,6-dichloro-2-methoxybenzoic acid

4. a. Rank the chemicals in order of their persistence in soil.

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4. b. Which herbicide(s) are both soil and foliar active.

4. c. What is the herbicide family and mode of action of

A.

B.

C.

15 points

5. For each of the following characteristics, list the mode(s) of action that have that characteristic. Use only the six modes of action discussed in lecture. Be careful here, if you are not sure of an answer, do not guess. The question is graded as follows: +1 point for each correct answer, -1 point for each missing answer, -0.5 point for each extra, incorrect answer.

translocated in the apoplast-

carotenoid pigment synthesis is affected-

annual and perennial plants controlled -

broadleaves primarily controlled-

primarily foliar active-

activity requires or is enhanced by sunlight-

plant death is rapid after application (often within hours)-

susceptible plants generally do not emerge from the soil -

25 points 6. Given the following structures, answer the following questions with the letter of the correct structure.

A. B. C.

6. a. What is the herbicide family and mode of action of these chemicals?

6. b. Rank the herbicides in order of least to most foliar activity. Explain the basis for your ranking (why are these herbicides different in terms of their foliar activity).

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6. c. Which herbicide is registered for use in legume crops. Give an example of a weed or type of weed that is controlled.

6.d. Which herbicide(s) are most susceptible to vapor drift? Explain.

6. e. Which herbicide(s) is/are most susceptible to physical drift? Explain.

EPWS/AGRO 311/511 Fall Semester 1996 EXAM III, November 25, 1996

Name

REMEMBER: I expect brief, legible, complete sentence answers to the following questions. A request for an explanation does require more than a single sentence answer, however. I will count off points for incorrect, extra information.

30 points 1. Consider the following structures to answer the following questions: for each herbicide, a. What is the herbicide family and mode of action. b. Is the herbicide soil active, foliar active, or both. c. Provide an example of a crop the herbicide is used in and a weed it controls.

A. [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene]

a. b. c.

B. methyl 2-[[[[[4-(dimethylamino)-6-(2,2,2-trifluoroethoxy)-1,3,5-triazin-2-yl]amino]carbonyl] amino]sulfonyl]-3-methylbenzoate

a. b. c.

C. N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine

a. b. c. D. 5-bromo-6-methyl-3-(1-methylpropyl)-2,4-(1H,3H)-pyrimidinedione

a. b. c.

E. (+)-ethyl 2-[4[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoate

a. b. c.

F. [1,1'-dimethyl-4,4'-bipyridinium ion (dichloride salt)]

a. b. c.

G. [isopropyl amine salt of N-(phosphonomethyl) glycine]

a. b. c.

H. 2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethyl-thien-3-yl-acetamide

a. b. c.

I. 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid

a. b. c.

J. N’(3,4-dichlorophenyl)-N-methoxy-N-methylurea

a. b. c.

5 points 2. a. How does soil pH influence biological activity, soil persistence, and soil mobility of the sulfonyl urea herbicides. Explain thoroughly.

15 points 3. Consider the following herbicides to answer the following questions. A. B. N,N'-bis(1-methylethyl)-6-(methylthio)- 6-chloro-N,N'-bis(1-methylethyl)- 1,3,5-triazine-2,4-diamine 1,3,5-triazine-2,4-diamine

C. 6-methoxy-N,N'-bis(1-methylethyl)- 1,3,5-triazine-2,4-diamine

a. What is the herbicide family and mode of action of A. B. C.

b. What is the site of action of these three herbicides.

c. Give an example of a weed that each herbicide will control, a crop that the herbicide is used in, and how the herbicide would be applied (soil, foliar, or either method):

A.

B.

C.

d. Order the herbicides in terms of their selectivity from greatest to least.

> > >

15 points 4. You are growing continuous corn in a field that contains quite a bit of Johnsongrass. You need to begin managing the Johnsongrass before it takes over the field. You look up your herbicide alternatives for Johnsongrass management in corn production and find two possible herbicides: nicosulfuron (2-[[[[(4,6-dimethoxy-pyrimidin-2-yl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboximide) or EPTC (S-ethyl dipropylcarbamothioate).

a. What is the herbicide family and mode of action of each of these products. How is (must be) each applied (explain, based on the general characteristics of each family). Nicosulfuron-

EPTC-

b. What major concerns would you have if you decided to use one of these products exclusively for Johnsongrass management (explain based on the general characteristics of each herbicide family). Nicosulfuron-

EPTC-

c. What do you plan/recommend to do to manage the Johnsongrass in this field?

20 points 5. You are consulting with a turf manager who has been using pendimethalin (N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitro-benzenamine) in bermudagrass turf for the control of crabgrass and other annual grasses for several years. They apply the product in spring every year because crabgrass is a summer annual weed. They were unhappy with the crabgrass control on the west side of the turf area this year and are asking your opinion about the problem. You talk to them for a considerable time and find out these additional details about the management this year: They began their application on the east side of the field and finished on the west side. In addition, they ran out of product 3/4 of the way through the job and it was three days before they were able to purchase more pendimethalin and complete the application. They watered the entire turf area daily using sprinkler irrigation. The weather was unusually warm the week prior to and during the time they applied the treatment.

a. What is the herbicide family, mode of action, and site of action.

b. Would you expect this herbicide to control the annual grass weeds?

c. What is the reason for the lack of weed control on the west side of the turf area?explain.

d. What do you recommend they do to control the weeds this year and what do you recommend they do to avoid the problem next year?

15 points 6. For each of the following situations, list the herbicide family(ies) that might be used to control the weeds and how the herbicide would be applied. a. Yellow nutsedge in turf.

b. Annual broadleaf weeds in winter wheat.

c. A combination of annual and perennial grasses and small (young) broadleaf weeds growing in cotton.

d. Annual grass and broadleaf weeds growing in onions that have not emerged.

e. Silverleaf nightshade (creeping perennial broadleaf) growing in an ornamental bed. FOR MY INFORMATION: PLEASE ANSWER THE FOLLOWING QUESTIONS!! This is your opportunity to provide input concerning topics for the final week of the semester and the final exam.

I. What 2 weed management situations are you most interested in discussing. List in order of preference. The situation should be a crop or weed problem (we would then discuss overall management strategies for the crop or the weed in a number of crops).

1. 2.

I will rank your answers and we will discuss the situations in order of expressed interest.

II. Final exam format; the exam will be 100% comprehensive - please circle the letter of your preference (no exam is not a choice!)

a. Closed book/closed note. b. Open book/open note. c. 50% closed book. 50% open book d. my choice.

EPWS 311/511 

FINAL EXAM 

December 11, 1996

CLOSED BOOK EXAM: You are NOT to use your book or class notes to answer the following questions. I expect legible, clear, complete sentence answers to the questions. I will deduct points for extra, incorrect information.

I. (25 points)

A number of plant species (Russian thistle, Palmer amaranth, field bindweed, Johnsongrass, khakiweed, prostrate spurge, yellow nutsedge, etc.) are considered to be problem weeds in New Mexico. You are a county extension agent speaking to a local civic organization in Las Cruces. A member of the group asks you "since these plants are weeds, is volunteer cotton growing in a chile pepper field also a weed? Why?" Please answer the question completely and use examples to discuss your response. II. (25 points)

Consider the following two scenarios to answer the following questions: A. Farmer Jones has a field of corn that has been treated every year for 10 years with atrazine (6-chloro-N-ethyl-N’-(1-methylethyl)-1,3,5-triazine-2,4-diamine) to control the annual broadleaf weeds; Palmer amaranth, kochia, and tall morningglory. The effectiveness of the herbicide treatment has been deteriorating over the past five years. The major weeds are now Palmer amaranth and kochia.

B. Farmer Jones has another field where cotton has been treated every year for 10 years with trifluralin (2,6-dinitro-N,N’-dipropyl-4-(trifluoromethyl)benzenamine) to control the annual grass weeds; barnyardgrass, crabgrass, and goosegrass. The effectiveness of the herbicide treatment has been deteriorating over the past five years in this field as well. The major weeds are now tall morningglory and spurred anoda.

Explain to Farmer Jones the reason for the poor weed control in each of the fields. Are the problems in each of these fields solely related to the use of herbicides or could they happen with other management practices as well? Explain. What would you recommend Farmer Jones do in each of these fields to remedy the problem? III. (25 points)

The following weeds are present on 20 acres of land you just purchased:

Palmer amaranth (annual broadleaf), emerges mid March barnyardgrass (annual grass), emerges mid March London rocket (annual broadleaf), emerges mid September common bermudagrass (creeping perennial), greens up around April 1 yellow nutsedge (creeping perennial), emerges early April muskthistle (biennial broadleaf), emerges March spurred anoda (annual broadleaf), emerges mid-April kochia (annual broadleaf), emerges early February

You want to take approximately one acre of land, build a home and landscape the area around the home with grass and ornamentals (herbaceous and woody). You decide to plant pecan trees on four acres and will plant annual row crops (both summer and winter crops) on the remainder.

Which of the listed weeds will be a problem in each of these vegetation types, now and 10 years from now? Are these the only weeds you will need to worry about over the next 10 years? What will you do to avoid additional problems? Develop a weed management strategy for your land (I am interested in concepts/strategies for each of the vegetation types; use specific examples and recommendations to enhance your discussion). Explain all of your responses. IV. (25 points)

Discuss three of the following five scenarios. Explain the probable cause of the problem and your recommendation for solving the problem now and avoiding the problem in the future.

1. Farmer Jones has a problem with lack of weed control in a field of pinto beans. A postemergence treatment of imazethapyr (2-[4,5-dihydro-4-methyl-4-(1-methylethyl)5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid) plus a surfactant was applied to beans that were about 6 inches tall to control annual broadleaf weeds. The weed control is variable throughout the field; the pattern is almost wavelike (IE good weed control for several feet then a couple of feet of poor weed control, then good control for several feet to yards and then a short section of poor control within a single spray swath - the pattern is not uniform from swath to swath nor is it related to soil texture differences in the field. The wave is always in the same direction, however.). The beans were not affected by the treatment. The application was made with a tractor sprayer and the calibration, nozzle size, etc. were all correct. Also, the tractor speed was determined to be constant. The day of the application was clear, temperatures were normal for the season, and winds were 0 to 6 mph with occasional higher gusts, the wind direction was perpendicular to the crop rows.

2. 2,4-D amine (amine salt of 2,4-dichloro(phenoxy acetic)acid) was sprayed as a postemergence treatment on a golf course for broadleaf weed control. The application was made with a tractor sprayer; you determine that the calibration was correct. The environmental conditions during application were good; clear skies and a light breeze registering 0 to 3 mph in the direction of a grape vineyard on the neighboring property. The owner is threatening to sue the golf course for damages to the grapes caused by the treatment. You are the lucky one and get the job of inspecting the irate grape owner’s damaged grapes. You look throughout the vineyard and find that the symptoms are widespread and consist primarily of large necrotic spots on the grape leaves.

3. Farmer Jones has a problem with lack of weed control. Norflurazon (4-chloro-5-(methylamino)-2-(3-(trifluoromethyl)phenyl)-3(2H)-pyridazinone) was applied as a preplant incorporated treatment in cotton to control annual grasses. The soil texture is a clay with 1% organic matter. One inch of rain fell two days prior to treating the field. The application equipment was accurately set up and calibrated. The environmental conditions at application included partly cloudy skies and wind at 3 to 5 mph perpendicular to the direction of travel. The rate of application was appropriate for the soil texture. The treatment was applied and incorporated with a disk in the same direction (parallel to) as the planted rows of cotton. The problem is that streaks of grass weeds emerged throughout the field. The streaks run parallel to the rows of cotton. Injured grasses are bleached white or dead; noninjured grasses in the streaks are green with occasional white areas on the older leaves. 4. Oust® 75 DG (sulfometuron, methyl 2-[[[[(4,6-dimethyl-2-pyrimidinyl)amino]carbonyl] amino]sulfonyl]benzoate) was applied as a postemergence treatment for the control of annual and perennial weeds (and release of common bermudagrass to aid with erosion control) along a highway right-of-way with mixed success. Calibration was accurate and the application was made under cloudy skies (no rain) and 2 to 3 mph winds. One spray tank treats approximately 20 miles of highway (500 gal spray tank, 10 gpa, 20 foot spray swath). A pattern is observed as you drive along each 20 mile stretch of treated highway going in the same direction as the spray truck did when applying the treatment. Complete vegetation control is achieved, including death of the bermudagrass, over the first five miles. Over the next 10 miles, the vegetation begins to survive (first section, bermudagrass is the only species to survive the treatment; then as you drive further additional species survive) the treatment and grow. Symptoms are stunting, necrosis of the apical meristems, chlorosis and/or reddening of the tissues. By the final five miles of the sprayed highway right-of-way per tank, no control or injury of any plant species is visible.

5. Describe weed management in the 21st century. What tools/techniques will be available and used by vegetation managers in the next century?