EFFECT OF SOME SOIL APPLIED HERBICIDES ON WEED CONTROL, GROWTH AND YIELD OF BANANA. (Musa acuminata,aaa)

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1 EFFECT OF SOME SOIL APPLIED HERBICIDES ON WEED CONTROL, GROWTH AND YIELD OF BANANA (Musa acuminata,aaa) By Ahmed Hassan Abdel aziz B.Sc. (Agric.)) 1981 University of Alexandria (Egypt) Supervisor: Dr. Salah EL tom EL amin Associate Professor A thesis submitted to the University of Khartoum in partial fulfillment for the requirement of the degree of Master science (Agric.) Department of Crop Protection Faculty of Agriculture University of Khartoum September 2003

2 بسم االله الرحمن الرحيم ] ربي أشرح لي صدري ويسر لي أمري وأحلل عقدة من لساني يفقهوا قولي [ ω سورة طه

3 ACKNOWLEDGEMENT My prayers and thanks to Almighty Alla who afford me the health to complete this work. I am greatly indebted to my supervisor Dr. Salah EL tom EL amin for his encouragement, continous help and support, kindness, guidance and patience through out the study. I would like to express deep appreciation to my brother Salah Babker and all the staff of Kassala Agricultural Reasrch Station for offering the site of field experiment and continuos help throughout the practical work, also my thanks to the farmer Ali Ebrahim for offering the other site of the field experiment. My thanks are due to my colleague Hassan Khaleel and the staff of department of crop protection. Due thanks are extended to my brother Abd EL monum, Walled for help me to compelete this work.

4 Contents Item Page no LIST OF TABLES I ACKNOWLEDGMENT ARABIC ABSTRACT ENGLISH ABSTRACT IV CHAPTER ONE: INTRODUCTION CHAPTER TWO: LITERATURE REVIEW 2.1. Damage caused by weeds in agriculture Losses in different crops due to weeds The use of herbicides for weed control in Sudan Chemical weed control in banana Classification of herbicides Soil-applied herbicides Classification Factors influencing activity of soil-applied herbicides Edaphic factors a\ Soil organic matter and clay content b\ Soil ph c/ Soil noisture d/ Nutrient status of soil e/ Soil structure and texture Climatic factors a/ Light b/ Moisture c/ Temperature Properties of soil-applied herbicides

5 Lipophilicity Water solubility and mobilityin soil The fate of soil-applied herbicides in the soil Uptake and metabolism by plant Leaching Volatilization Photodecomposition Adsorption Degradation by soil microorgansims Chemical decomposition Selectivity of herbicides Herbicides used in present investigation a/ Stomp b/ Goal c/ Druid d/ Round-up CHAPTER THREE 3.1 Experimental sites Land preparation planting materials The herbicides used Propping Data collection Crop Weeds Statistical analysis CHAPTER FOUR 4.1 effect of herbicides on some growth components Plant height (cm) Pseudostem girth

6 4.1.3 Number of leaves Effect of herbicides on some yield components Bunch weight (Kg) Number of hands per bunch Number of fingers per hand Effect of herbicides on weed weed control CHAPER FIVE DISSCUSSION SUMMARY AND CONCLUSIONS REFERENCES APPENDICES

7 LIST OF TABLE Table no Page 1. Effect of herbicides treatments on plant height (cm) Effect of herbicides treatments on pseudostem girth (cm) Effect of herbicides treatments on number of leaves Effect of herbicides treatments on bunch weight (Kg) Effect of herbicides treatments on number of hands per bunch Effect of herbicides treatments on number of fingers per hand Effect of herbicides treatments on weed control/m Effect of herbicides treatments on weed biomass g/ m List of the dominant weed plants in experimental sites 37

8 ملخص الا طروحة تمت هذه التجربة خلال موسمي الخريف للا عوام 2000 و بمزرعة البحوث الزراعية ومزرعة ا حد مزارعي الموز بولاية كسلا بالسودان لا ختبار فاعلية ثلاثة مبيدات للحشاي ش هي : أستومب ) L pendimethalin ( 1.0 and 2.0 ودایرون 2.0Kg) (1.0 and dichlorfenidimوقول (1.0L oxyflurofen 0.5) and و خليط من دایرون + أستومب و دایرون + قول بجرعة L) ( 1,0 Kg +0.5 علي بجرعة( 1.0L + (1.0 Kg إنتاج ونمو الموز. أظهرت الدراسة أن المبيدات المستخدمة بجرعاتها المختلفة ومخاليطها أدت إلي زیادة معنویة في نمو محصول الموز متمثلة في طول النبات وسمك الساق الكاذبة وعدد الا وراق خلال الموسمين آما أدن إلي زیادة معنویة في إنتاج الموز متمثلة في وزن السبيطة وعدد الكفوف في السبيطة وعدد الا صابع في الكف رقم ) 2 ( مقارنة بالشاهد خلال الموسمين. آما دلت النتاي ج علي أن العزیق اليدوي أدي إلي زیادة معنویة في نمو وإنتاج الموز مقارنة بالجرعات العالية للمبيدات المستخدمة في التجربة مقارنة بالشاهد. بدراسة أثر هذه المبيدات في مكافحة الحشاي ش أظهرت جميع المبيدات بجرعاتها العالية ومخاليطها المستخدمة في هذه التجربة آفاءة متوسطة إلي عالية في مكافحة الحشاي ش وخاصة الحولية یدل عليها عدد الحشاي ش والوزن الجاف لها ولقد أظهر مبيد الدایرون بجرعة 2 آجم / هيكتار آفاءة عالية في مكافحة الحشاي ش الحولية. أوضحت الدراسة أن بعض الحشاي ش مثل ) Datura innoxia Mill السكران ( و Argemone mexicana (ابوشوك) و ) Amaranthus vidiris لسان الطير) اظهرت مقا ومه للمبيدات المستخد همة في هذة التجربة.

9 ABSTRACT This study was conducted during the autumn seasons of 2000/01 and 2001/02 at the Research Station Farm and a private farm for growing banana at Kassala State, Sudan. The purpose of the study was to evaluate the efficacy of three pre-emergence herbicides: pendimethalin 500 at ( L/ha), dichlorfenidim 80 at ( Kg/ha) and oxyflurofen 20 at ( L/ha) and two mixture: dichlorfenidim+pendimethalin at (1.0Kg+ 1.0L) and dichlorfenidim +oxyflurofen at (1.0Kg +0.5L) on growth and yield of banana crop. Results showed that all herbicides at different rates and their mixture in both seasons gave significant increases on banana growth parameters including plant height, pseudostem girth and number of leaves as compared to the control. Final yield as expressed in term of bunch weight, number of hands per bunch and number of fingers per hand 2 was significantly increased due to the use of the above-mentioned herbicides. Moreover manual weeding showed significant increases in banana growth and yield parameters which were sometimes comparable to the herbicides with their high rates. However, during the two growing seasons Diuron at (2.0Kg) solely gave significantly the best results in both growth and yield parameters. The used herbicides proved an effective and lasting weed control of both broadleaved and narrow-leaved annual weeds in the experimental sites as measured by weed count and weed biomass. The best percent weed control was recorded with Diuron (2.0Kg). Some weed species in the experimental sites such as Datura innoxia Mill, Argmone mexicana L and Amaranthus viridis L were not effectively controlled with the used herbicides.

10 CHAPTER ONE INTRODUCTION Bananas (Musa sp.) have played important roles in the history of human civilization. The origin of greatest diversity of wild Musa species is in Indochina and Southeast Asia where the earliest domestication is considered to have occurred (Simmonds, 1962). Banana belongs to the family Musacease and the genus Musa. The different banana cultivars have their origins in the two wild species: accuminata and balbisiana of the Eumusa series of the genus Musa (Simmonds, 1962). Banana is the fourth most important food crop after sorghum, millet and wheat in developing countries with a combined production of more than 90 millions tones (FAO, 1999). They rank as the second largest fruit crop in the world after citrus. It is important stable food in sub-saharan Africa, Tropical America, Asia and Pacific. Most of the world production is consumed locally leaving 15% for export (Ali, et al 2003). In Sudan banana is produced commercially in small-scattered gardens along the Nile banks and in large plantations in Kassala. The banana cultivar Dwarf Cavendish covers most of the area (95%) under banana production (Oritiz, 1996). This cultivar considered as the most adapted banana cultivar to different climatic conditions (Samson, 1980). Seemingly the crop is well adapted to the warm dry climate under light fertile soil. Banana is a fruit popular for its flavour, its texture and for its great convenience. Banana is of high nutritional values. They are 99.5% fat free, with no saturated fats,

11 no cholesterol and no sodium. It can usefully contribute to the vitamin A, B1, B2, B3, B6 and C and contain minerals such as potassium and phosphorous, essential for good health (Chandler, 1995). Βανανασ προδυχτιον ιν Συδαν δοεσ νοτ συφφε ρ ανψ πεστ ανδ δισεασεσ, εξχεπτ νεµατοδεσ. Ηοωεϖερ ηεαϖψ ινφεστατιον οφ ωεεδσ χονστι τυτεσ τηε µαιν οβσταχλε φορ ιτσ προδυχτιον. Ιν τηε Συδαν ωεεδσ ιν βανανα αρε µαινλψ ρεµοϖεδ µανυαλλψ, υσινγ σπεχιαλ τοολσ. Ωεεδσ χαν β ε χοντρολλεδ βψ µεχηανιχαλ ανδ χηεµιχαλ µε ανσ, ωιτη τηε λαττερ µετηοδ βεινγ ινχρεασινγ λψ αδοπτεδ ιν ϖαριουσ παρτ οφ τηε ωορλδ. Σο µε ηερβιχιδεσ, ωηιχη προϖεδ το βε υσεφυλ ιν οτηερ βανανα προδυχινγ χουντριεσ ανδ χυρρε

12 ντλψ αϖαιλαβλε ιν τηε Συδαν, ινχλυδε ιυρον, Ατραζινε ανδ Σιµαζινε ασ πρε εµεργενχε ηερ βιχιδεσ, Παραθυατ, γλψπηοσατε ανδ Βαστα α σ ποστ εµεργενχε ηερβιχιδεσ. The objective of this investigation aimed at: Studying and comparing the effect of three pre-emergence soil-applied herbicides, namely Stomp (pendimethalin), Diuron, (dichlorfenidim) and Goal (oxyflurofen) and two mixtures from Diuron+Goal and Diuron+Stomp on degree of weed control and growth and yield of banana.

13 CHAPTER TWO LITERATURE REVIEW 2-1 Damage caused by weeds in agriculture Ωεεδσ αρε υσυαλλψ τηε ωιλδ πλαντσ τηατ γρο ω ωιτη χροπσ ανδ παστυρεσ. Τηεψ χοντριβυτε λεσσ το τηε βενεφιτ οφ τηε φαρµερ τηαν τηεψ τακε φροµ ηιµ ιν ρεδυχινγ ψιελδ ορ προφιτ (Σω αρβριχκ ανδ Μερχαδο, 1987). Ιν αδδιτιον το χο µπετιτιον, ωεεδσ χαν ιντερφερε νεγατιϖελψ ωι τη χυλτυραλ ανδ ηαρϖεστ πραχτιχεσ. Σοµε ωε εδ σπεχιεσ αρε ποισονουσ ανδ / ορ ηαρβουρ π εστσ ανδ δισεασεσ. Τηεψ αλσο χαυσε δαµαγε βψ ρεδυχτιον ιν λανδ ϖαλυε ανδ ρεδυχτιον ιν φαρµ λοαµ, λοσσ οφ θυαλιτψ οφ χροπ προδυχε

14 δ ανδ ρεδυχεδ ηυµαν εφφιχιενχψ. Αθυατιχ ωεε δσ οβστρυχτ ωατερ χαναλσ ανδ ριϖερσ ανδ χ αυσε λοσσ οφ ωατερ τηρουγη εϖαπο τρανσπι ρατιον. Τηεψ αλσο ρεδυχε τηε θυαντιτψ ανδ θ υαλιτψ οφ λιφε στοχκ προδυχτσ (Ραο 1983; Βρ αυν, ετ αλ 1991). Βραυν ετ αλ (1991) ασσυµε τηατ χροπσ ωερε µ οστ συσχεπτιβλε το ωεεδ χοµπετιτιον ιν τηε φι ρστ τηιρδ οφ τηειρ τοταλ λιφεσπαν. 2 2 Λοσσεσ ιν διφφερεντ χροπσ δυε το ωεεδσ Ιν Ωεστ Αφριχα Ωιλσον (1987) στατεδ τηατ, πο ορ ωεεδ χοντρολ ιν αλλ χροπσ, ωηετηερ φιελδ ορ ηορτιχυλτυραλ ωασ α µαϕορ φαχτορ ενηα νχινγ ψιελδ δεχλινε. Βραυν (1991) σηοωεδ τηα

15 τ τηε ποτεντιαλ ψιελδ λοσσεσ ιν διφφερεντ χρο πσ τηρουγη υνρεστριχτεδ ωεεδ γροωτη ωασ φο υνδ το βε 61 80% ιν γρουνδνυτ, 33% ιν σοψ βε αν, 28% ιν ωηεατ ανδ 31 99% ιν εγγπλαντ. Ιν Κενανα, σιµιλαρ ορ ιδεντιχαλ ωεεδ δενσιτιεσ ρεδυχεδ τηε σεεδ οφ χοττον, γρουνδνυτ ανδ γρ αιν σοργηυµ βψ 74, 73 ανδ 47% ρεσπεχτιϖελψ (Βεσηιρ, 1970). Ιν Συδαν ιφ νο ηανδ ωεεδινγ ισ χαρριεδ ουτ 60 90% οφ ποτεντιαλ ψιελδ ισ λο στ ειτηερ ιν ραιν φεδ αγριχυλτυρε (Ηαµδουν α νδ ΕΛ. Τιγανι, 1977) ορ ιν ιρριγατεδ αρεασ (Ιδρ ισ, 1970)

16 2 3 Τηε υσε οφ ηερβιχιδεσ φορ ωεεδ χοντρολ ι ν Συδαν More than 80% of the population in Sudan lives in the rural areas and is engaged in one way or another in agricultural production (Braun et al. 1991). They added that, in recent years the available labour was unable to cope with the intensive weed growth nor carry out the optimum number of weeding and serious crop losses are usually encountered. The scarcity of labour due to the expansion of cropped areas, the infestation of cropping, the continued movement of the younger generations to Urban areas, and abroad, the attendance of farmer s sons and daughters to schools and the reluctance of farm labour to the tedious hand weeding operations, have all led to considerable rise in the cost of hand weeding and to a costly increase in annual and perennial weed infestation. Such a situation encouraged the use of herbicides in cotton, groundnut, sorghum, some vegetables and tree crops (Braun et al, 1991). 2 4 Χηεµιχαλ ωεεδ χοντρολ ιν βανανα Αχχορδινγ το Ροβινσον (1995) ωηεν βανανα π λαντσ αρε ταλλ ενουγη (1 1.5 µ) σελεχτιϖε ηε ρβιχιδε χαν βε υσεδ το χοντρολ ωεεδσ ωιτηουτ δαµαγινγ βανανα λεαϖεσ. Ηερβιχιδεσ γενερα

17 λλψ ρεγιστερεδ φορ υσε ιν βανανα αρε Αµετρ ψνε, ιυρον, Παραθυατ ανδ Ρουνδ υπ (Ροβινσ ον, 1995). Τηε πρε εµεργενχε ηερβιχιδε Αµετρ ψνε χαν συππρεσσ γενεραλ ωεεδ γροωτη φορ 3 4 µοντησ αφτερ αππλιχατιον. Ροβινσον (1995) ρεπορτεδ τηατ ωηεν τηε πλαν τατιον ισ αβουτ 6 µοντη ολδ, τηε χονταχτ ηερ βιχιδε παραθυατ χαν βε αππλιεδ το τηε ωεεδ χ οϖερ ανδ ιτ ισ εσπεχιαλλψ εφφεχτιϖε ον βροα δ λεαϖεδ αννυαλ ωεεδσ. Ιν νεωλψ δεϖελοπεδ βανανα φιελδ περεννιαλσ γρασσ σπεχιεσ χαν βυιλδ υπ, τηεσε αρε χοµπετιτιϖε ωιτη βανανα ανδ σηουλδ βε σποτ σπραψεδ ωιτη σψστεµιχ ηερβιχιδεσ λικε γλψπηοσατε (Ροβινσον. 1995).

18 Λυι ετ αλ (1981) φουνδ τηατ φουρ ποστ εµεργ ενχε τρεατµεντσ αππλιεδ ονε αφτερ ανοτηερ ω ιτη γλψπηοσατε ατ Λ/ηα γαϖε 96% χοντ ρολ οφ γρασσεσ ανδ βροαδ λεαφ ωεεδσ ιν βαν ανα φιελδσ. Ασ ρεπορτεδ βψ Αχηαρδ (1993) τη ε ηερβιχιδε παραθυατ, γλψπηοσατε αρε πρεσε ντλψ υσεδ φορ ωεεδ ιν ινδυστριαλ βανανα πλ αντατιονσ. Γλψπηοσατε ισ ηιγηλψ εφφιχιεντ αγαινστ α ωιδε ρανγε οφ ωεεδσ. Μισηρα ετ αλ (1984) ωορκινγ ωιτη ιυρον 4 Κγ/ηα ανδ Σιµαζ ινε 6 Κγ/ηα αππλιεδ ον τηε φιρστ δαψ αφτερ π

19 λαντινγ Χαϖενδιση βανανα, φουνδ τηατ τηε ψ ιελδσ ωερε ηιγηεστ ον πλοτσ τρεατεδ ωιτη Σιµ αζινε 6Κγ/ηα ανδ ιυρον 4Κγ/ηα, ναµελψ, ανδ 29.9 τ/ηα ρεσπεχτιϖελψ ασ χοµπαρεδ το 22.8 τ/ηα ιν τηε χοντρολ. Περεζ ετ αλ (1977) ρ επορτεδ τηατ ιυρον ατ 3.2 Κγ/ηα ορ σιµαζινε (2.4 Κγ/ηα) +Αµτρψνε (2.4Κγ/ηα) αππλιεδ αφτ ερ πλαντινγ ανδ αγαιν 6 µοντησ λατερ γαϖε γ οοδ χοντρολ ανδ διδ νοτ δαµαγε τηε χροπ. Ροδ ριγυεσ ετ αλ (1978) στυδιεδ Σιµαζινε ανδ ιυρ ον ατ τηε ρατε οφ 3.2 Κγ/ηα ανδ 4.8 Κγ/ηα, ρεσ πεχτιϖελψ ανδ Σιµαζινε +Αµετρψνε ατ τηε ρα τε οφ ανδ Κγ/ηα, ρεσπεχτιϖελ ψ εαχη οφ τηεµ ωερε αππλιεδ ιν α 6 µοντη ιντε

20 ρϖαλσ. Τηεψ φουνδ τηατ, τηε ηιγηερ ρατεσ οφ αλλ τηε χοµπουνδσ υσεδ χοντρολλεδ ωεεδσ ω ελλ. Ραµαδασσ ετ αλ (1980) ρεπορτεδ τηατ πρ ε εµεργενχε αππλιχατιον οφ ιυρον ατ 4Κγ/η α χοντρολλεδ αννυαλ γρασσ ανδ βροαδ λεαϖ εδ ωεεδσ ωιτηουτ ρεδυχινγ βανανα ψιελδ ορ θ υαλιτψ. Αχχορδινγ το Αχηαρδ (1993) Γλψπηο σατε ισ τηε ρεφερενχε ηερβιχιδε συιτεδ φορ β ανανα πλαντατιονσ ιν Χαµερον. Ιτ ωασ φουνδ το βε ηιγηλψ εφφεχτιϖε αγαινστ α ωιδε ρανγε οφ ωεεδσ ανδ ωιτη λονγ λαστινγ ρεσιδυαλ εφφ εχτσ. Αχηαρδ (1993) ρεχοµµενδεδ τηατ τηε αππλιχα τιον οφ γλψπηοσατε σηουλδ βε υνδερτακεν ωι

21 τη χαρε σινχε ιτ ηασ στρονγ πηψτοτοξιχ εφφε χτσ ον βανανα πλαντσ υπον χονταχτ. ςαριου σ χοµβινατιονσ ανδ ρατεσ οφ ιυρον, Γεσαπα ξ ανδ Γεσαπριµ ωερε αππλιεδ το βανανα χϖ. Χαϖενδιση Ροβυστα πρε πλαντινγ. Αλλ τρεατ µεντσ γαϖε 79 83% ωεεδ χοντρολ υπ το 80 δα ψσ. Ψιελδσ ωερε 60.9 το62.6 τ/ηα ιν ηερβιχιδε σ τρεατεδ πλοτσ, 62.9 τ/ηα ιν πλοτσ ωιτη µανυ αλ ανδ µεχηανιχαλ ωεεδινγ ανδ ιν υντρε ατεδ πλοτσ (ςενερχο. 1980). Ηερρερα Γονζαλεζ (1978) ρεπορτεδ τηατ Ατα τριλ ( ιυρον + αµινοτριαζολε) ατ 8 Κγ (Προδυ

22 χτ/ηα), γλψπηοσατε ατ 5.0 λιτερ (Προδυχτ/ηα) αρε τηε µοστ εφφεχτιϖε ιν χοντρολλινγ Χψπε ρυσ σππ. Αχχορδινγ το Νυβε ετ αλ. (1991) πρε εµεργενχε ιυρον ατ 2.5 Κγ/ηα ανδ Παραθυα τ ατ 1.2 Κγ/ηα ινχρεασεδ βανανα βυνχη ωειγη τ φροµ χοντρολ ϖαλυεσ οφ 7.3 Κγ το α µαξιµυ µ οφ 7.63 Κγ. ιυρον ατ 2.5 Κγ/ηα ωασ τηε ονλ ψ τρεατµεντ τηατ ινχρεασεδ τηε νυµβερ οφ ηα νδσ φροµ χοντρολ ϖαλυεσ οφ 5.27 το 5.33 ιυ ρον (ατ 1.25 ανδ 2.5 Κγ), Παραθυατ (ατ 0.8 αν δ 1.2 Κγ) ανδ 2,4, +δαλαπον ινχρεασεδ τηε νυ µβερ οφ φινγερσ φροµ χοντρολ ϖαλυεσ οφ 42.2 το Χηαλλα ετ αλ (1990) φουνδ τη ατ ιυρον 2.0 Κγ φορ τηε χοντρολ οφ ωεεδσ ιν

23 βανανα ρεσυλτεδ ιν νετ προφιτ οϖερ ηανδωεε δινγ. 2.5 Clssification of herbicides According to Rao (1983) herbicides are divided in accordance to the method of application, in two large groups: soil- applied herbicides and foliage applied herbicides. They are also divided according to time of application into: a) Pre-plant herbicides: herbicides applied to the soil before the crop is planted. b) Pre-emergence herbicides: ηερβιχιδεσ αππλιεδ αφτερ τηε χ ροπ ηασ βεεν πλαντεδ, βυτ πριο ρ το εµεργενχε οφ τηε χροπ ορ ω εεδ ορ βοτη. χ) Ποστ εµεργενχε ηερβιχιδεσ: ηερβιχιδεσ αππλιεδ αφτερ τηε χροπσ ορ ωεεδσ ορ βοτη ηαϖε εµεργεδ φροµ τηε σοιλ.

24 Αλλ ηερβιχιδεσ αππλιεδ ασ πρε εµεργενχε ανδ πρε πλαντ αρε χονσιδερεδ ασ σοιλ αππλιεδ ον εσ ανδ τηοσε αππλιεδ βοτη εµερ γενχε το τηε χροπ αρε ινχλυδεδ υνδερ φολιαγε αππλιεδ γρουπ Σοιλ αππλιεδ ηερβιχιδεσ Σινχε σοιλ αππλιεδ ηερβιχιδεσ ω ερε υσεδ ιν τηε πρεσεντ ρεσεαρχ η ωορκ ιτ ισ ωορτη χονχεντρατι νγ ον τηε µοστ ιµπορταντ χηαρα χτερσ ινχλυδε τηε φολλοωινγ:

25 Χλασσιφιχατι ον Αχχορδινγ το Ανδερσον (1977) σ οιλ αππλιεδ ηερβιχιδεσ αρε χλα σσιφιεδ (ον τηε βασισ οφ χηεµιχ αλ στρυχτυρε) ιντο οργανιχ ανδ ινοργανιχ χοµπουνδσ ινχλυδε συχη συλπηατεσ, νιτρατεσ, βορ ατεσ, χηλορατεσ ετχ. Οργανιχ χοµπουνδσ ινχλυδε αλ ιπηατιχ, βενζοιχ χαρβαµατεσ, α µιδεσ, δινιτροαντινε, νιτροπηεν ολσ, τριαζινε, υραχιλσ, συλφον υρεασ ανδ διπηενψλετηερσ.

26 φαχτορσ ινφλ υενχινγ αχτιϖιτψ οφ σοιλ αππλιεδ ηερβιχι δεσ Αφτερ ηερβιχιδεσ ρεαχη τηε σοι λ, ιτ ισ συβϕεχτεδ το ϖαριουσ ρ εαχτιονσ ωιτη σοιλ ανδ ενϖιρο νµενταλ φαχτορσ. Μοστ ιµπορτ αντ φαχτορσ ρεϖιεωεδ το ινφλυ ενχε σοιλ αππλιεδ ηερβιχιδεσ α ρε τηε φολλοωινγ: Εδαπηιχ φα χτορσ: a) Soil organic matter and clay content

27 Soil organic matter is the most significant factor affecting adsorption, desorption, and phytotoxicity. These are considered as the most important factors in reducing the phytotoxicity of dinitroaniline herb icides. It can be a major reason for the wide variation in plant response to a given herbicides concentration in the soil ( Elamin, 1991). According to Applebly (1985) organic matter can be a major reason for a wide variation in plant response to a given herbicide concentration in the soil.upchurch and Nason (1962) examined 12 different herbicides, and they found that the activity of those herbicides was highly correlated with soil organic matter content. b) Soil-pH Corbin and Upchurch (1967) showed that, soil ph may directly or indirectly influence the activity and detoxification of herbicides by affecting ionic or molecular character of chemicals, the ionic character of soil colloids, the cation exchange capacity and the inherent capacity of microbial population to attack a given herbicides. Harris and Warren (1964) found that, soil ph influence herbicide absorption and that

28 different herbicides responded differently to change in soil ph. Rao (1983) reported that, the degradation of atrazine occurred more rapidly when surface ph was less than 5.0 compared with a ph greater than 6.0. c) Soil moisture Urea herbicides like linuron and diuron toxicity increased in wetted soil, as water can compete for adsorption sites, thus cause more herbicides to be in soil solution and available for uptake (Elamin, 1991). Savage (1978) showed that, degradation of pendmethalin (Stomp) proceeded more under flooded anaerobic condition than under flooded aerobic conditions. Boldt and Barret (1989) indicated that an increased soil moisture coupled with a decreased soil temperature increased chloroacetamide phytotoxicity to corn seedling. d) Nutrient status of the soil The effects of soil nutrient levels on herbicides activity were small compared with those from other soil properties (Elamin, 1991). High level of phosphorus enhanced the action of amitrole, diuron, simazine and atrazine (Selman and

29 Upchurch, 1970; Sun and Adum, 1971). According to Stolp and Penny (1973) high level of phosphorus increased the phytotoxicity of diuron. e) Soil structure and texture Soil structure and texture (clay, silt and sand) are the important factor to be considered in the use of soilapplied herbicides. Braverman et al (1986) found that, the degradation rate of metolachor (Dual) was more rapid in silty loam soils than in silty clay soils. Carbamates and urea herbicides are considerably less toxic to weeds in a heavy organic soil than to the same weeds in light soil Hartly, (1964) Climatic factors Light, temperature and moisture are the main climatic factor to be considered when deeling with soil acting herbicides. a) Light Savage and Jordan (1980) indicated that shading from direct sun light greatly reduced the loss of fluchloralin and pendimethalin as compared to their exposure to full sunlight. According to Abadallah (1991) light assists herbicide penetration by stimulating stomatal opening and it also activates photosynthesis, some of the herbicides such as dinitroaniline are photodegraded by light, thus incorporation of such herbicides is recommended for

30 surface application. The effect of lights varies with duration and intensity. b) Moisture Moisture is important to bring the herbicides from the point of application to the site of action. According to Hartly (1976) herbicides applied to soil surface need to be moved into the soil by irrigation water or rainfall. Kern et al (1975) indicated that high soil moisture during periods of active plant growth is favourable for rapid root uptake of cyanazine which causes injury to corn. c) Temperature According to Elamin (1991) both air and soil temperature influence the performance of soil acting herbicides. Temperature influences herbicide activity in many ways and interacts with other environmental factors. It might also influence plant response by affecting herbicide availability in the soil, humidity gradient and therefore physiological process. Viger et al (1991) studied the influence of temperature on metolachlor observed that, injury to corn growth under cool temperature (13/12c ) day/night is more than when grown under warm temperature (30/21c ). Temperature and herbicides treatments significantly influenced some nutrient concentration in roots, stems and

31 leaves of plants compared to the untreated control (Tamo et al.1989) Properties of soil-applied herbicides Lipophilicity According to Elamin (1991) herbicides which are not electrically charged are bound by soil according to their oily i.e. polar compounds will associate with soil organic matter in preference to water. Very oily herbicide such as trifluralin are strongly bound in moist soils. Such strongly bound compound is usually volatile and work by evaporation and move to weed shoot as a vapour. Loss of such herbicides by evaporation from the soil surface can be a problem and that is why they are mechanically incorporated at application Water solubility and mobility in soil Mobility of herbicides within the soil either in aqueous phase or in gaseous state is a significant factor that will influence its bioactivity. However, it has been concluded that the aqueous movement of dinitroanaline has almost no effect on their herbicide efficacy. Numerous investigators found most the dinitroanaline herbicides move only slightly in leaching studies, remaining essentially where they applied. They have very low water solubility and their affinity to lipophilic substances contribute to this negligible mobility (Elamin, 1991) The fate of soil-applied herbicides in the soil

32 Herbicides reaching the soil become dissipated or removed in the following ways: uptake and metabolism by plant, volatilization, photodecomposition, adsorption, leaching, degradation by soil microorganism and chemical degradation (Rao, 1993) Uptake and metabolism by plant After application of herbicides onto or into the soil, the active compound may be taken up via the seed, the embryo the seedling of mature plant. Herbicides taken up by plants may be toxic or non-toxic, tolerant plant detoxify the product while susceptible plant are killed (Akobundu, 1987). The site of uptake of dinitroanaline is the shoot for monocots and the hypoctyl hook for dicot (Elamin, 1991). Whereas the site of action for them in monocots is coleptile. High levels of relative humidity increased dalapon uptake into plant by hydrating the cuticle (Jordan, 1977). Herbicides degradation inside plants may take place through: conjugation (amides), hydrolysis (ureas), demethoxylation (benzoic) and ring cleavage for diphenylethers and triazine (Akobundu, 1987) Leaching The extent to which soil-applied herbicide moves into the soil with water largely determines its efficacy and persistence, so herbicides which are applied to soil surface need to be moved into the soil by rainfall or irrigation water (Hartly, 1976), however further downward movement

33 can result in decrease weed control efficacy and damage deep rooted crops (Koren, 1972). Application of addition water also influence mobility of herbicide (Anderson, 1977). Addition of excess water was found to increase leaching of diphenamide (Dubey, et al 1965). Different herbicides vary in their mobility in soil. Diuron and linuron are considered as moderately mobile (Horowitz et al, 1974). According to Erichson, (1965) adsorption of herbicides by soil organic matter and onto clay minerals reduces or sometimes inhibits leaching. Monuron leaching was found to be greatly reduced in soils containing low sand, high clay and organic matter. Herbicides loss from the soil by leaching is influenced by soil drainage, the solubility of herbicide and the lack of adsorption; these are important factors in the loss of the phenoxykanoic acid and the chlorinated aliphatic acid from soil (Fletcher and Krikwood, 1982) Volatilization Volatilization of herbicide from soil is controlled by many variables including soil moisture content and direct sunlight (Savage and Jordan, 1980). Porosity is main soil property which affect volatilization through the affection of transfer of vapour by diffusion and this will bring soluble herbicides to the surface and increase volatilization (Anderson, 1977). Walker and Bond (1977) showed that, significant losses of pendimethalin from surface application may occur through volatilization

34 although these are greatly reduced when the soil surface is dry. These herbicides is more persistent when incorporated than applied to the soil surface Photodecomposition Soil applied herbicides are unstable under light and the decomposition of herbicides observed by many workers under field conditions, Savage and Jordan (1980) reported that shading from direct sunlight largely reduced the loss of fluchloralin and pendimethalin as compared to expoure of full sunlight. Hahn et al. (1969) observed the decomposition of substitued ureas like monuron, diuron under field condition Adsorption According to Rao (1983) adsorption is the major factor affecting the persistence and behaviour of herbicides in the soil. Strongly adsorbed herbicides decompose very slowly. Decomption is rapid in the case of herbicides, which are more freely available in soil solution Degradation by soil micro-organisms: Destruction of soil applied herbicides by microorganisms may occur rapidly if condition are proper for their growth in the soil. Barua et al (1990) indicated that pendimethalin degradation by several soil fungi provided a partial N-dealkylation followed by ring hydroxylation, nitro group reduction and complete N- dealkylation. Break down of the herbicide P. chloro-phenylmethyl carbamate and metamitron was done by arthrobacter sp. Engelhard et al (1982). According to Liu et al (1991) dechlorination was a major

35 transformation mechanism of metolachlor by three soil fungi: Streptomyces sp, Phanerchaetae chrysosprim, and Rhizoctonia porticola Chemical decomposition Soil applied herbicides undergo arrange of chemical reaction which lead to oxidation, reduction, hydrolysis or formation of more complex compounds (Anderson, 1977). Brown et al (1972) observed hydrolysis of herbicide cyanazine in acid and alkaline solution. Chemical decomposition needs higher energy and it is highly dependent on temperature (Bursche, 1961) Selectivity of soil acting-herbicides According to Gwynne and Murray (1985) the term selectivity refers as the situation where a herbicide reaches and destroys a vital function in one plant (weed) or group of plants (weeds) and does not cause simultaneous damage to anther crop. Holly (1976), Gwynne and Murray (1985) reported that selectivity could be achieved by various mechanisms: 1.By variation in position of root or shoot of plant to herbicides i.e Positional selectivity or depth protection (Walker, 1980) 2.Differences in degradation and metabolic rates, i.e. rapid conjugation of atrazine to harmless products before reaching the site of action.

36 2.6 Herbicides used in the persent investigation (a) Stomp 500 E.C. Molecular formula C1 3 H 19 N 2 O 4 Structure formula NO 2 CH 3 NHCH CH 2 CH 3 CH 3 NO 2 2 Trade name: Stomp, Porwal, Herbadox, Way-up and Go Go San Commen name: Pendimethalin Chemical family: Dinitroaniline Chemical name: N-(1- ethylpropyl) 4,3-dimethyl 2-6 dinitroobenze amine The used formulation is Stomp 500 E.C, an emulsifiuble concentrate containing 500 g/ liter active ingredient (Hance and Holly, 1990). It is a selective herbicide effective against most annual and several small seeded annual board-leaved weeds. It can be applied pre-emergence, after seeding in cereals, maize and rice or with shallow soil incorporation before seeding bean, cotton, groundnut and soybeans. In vegetable crops which it can be applied pre-emergence or pretransplanting. Also used to control suckers in tobacco. The product is proved by American Cyanamide Co.(Anon, 1993). Stomp as a dinitroaniline herbicide exerts its herbicidal effects by inhibiting both root and shoot growth and development by interfering

37 with cell divission (Murray et al.1979 ; Huffman and comper, (1978). Stomp inhibits cell division. Several biochemical processes can be altered such as photosynthesis, RNA and protein synthesis, Lipid synthesis and oxidation phosphorylation (Roberts, 1982).

38 (a) Goal Molecular formula: C 15 H 17 O 4 F 3 Cl N Strutural formula: CF 3 O NO 2 OCH 3 H 3 Cl Trade name: Goal Chemical name: Oxyflurofen Chemical name: 2-chloro-1-(3 ethoxy-4 nitrophenoxy)-4- methyl benzene. Goal is a diphenyl ether compound with benzene rings joined together through Oxygen. Mainly applied as surface pre-emergence spray, for controlling germinating annual grasses and broad-leaved weeds in beans, onion, sunflower, citruses, garlic, cabbage and other crops (Robrets, 1982). Some perennials weeds can be controlled with oxyflurofen at a certain stage of growth. It can persist in the soil for several months after application of higher doses to the soil surface. It is relatively insoluble in water and hence do not readily leach (Roberts, 1982 and Mohamed, 1995). It is not absorbed by roots nor foliage but damages shoots. When

39 Goal is applied to foliage causes necrosis, while pre-emergence application inhibits seed germination, early seeding growth and meristematic activity (Roberts, 1982 and Mohamed, 1995). The formulation used was Goal, 200 E.C. (c ) Diuron 80 Molecular formula: C 9 H 10 C l2 N 2 O Structural formula Cl CH 3 Cl NH-C-N O CH 3 Trade name: Diuron, Diater, Karmex, Di-on and Unidron Common name: Dichlrofenidim Chemical family : Substituted urea Chemical name: 3-(3,4 dichlorophenyl)-1,1- dimethyl urea Diuron is asubstituted urea herbicides used to control a wide variety of annual and perennial broad-leaf and grassy weeds. It is used to control weeds and mosses on non-crop areas and among many agricultureal crops such as fruits, cotton, sugar cane and legumes (Beste. 1983). Diuron translocated via the apoplastic system, whether absorption has

40 occurred via the root.inhibition of photosynesis is generally considered to be the primary, though not the necessarily the only mechanism of action. Mammalin toxicity is low (Roberts, 1982).

41 (d ) Round-up O Structure formula HO.CO-CH 2 NHCH 2 P (OH) 2 Glyphosate, introduced in 1977 by Monsanto, is aphosphonate derivative of the amino-acid glycine. It is primarily foliar-acting with no activity through the soil. It is active on most annual and perennial weeds and indeed most green plants. It is approved for use before planting and drilling of all outdoor crops, on non-crop land, for emergent aquatic weeds, as adirect spray in many furit trees and forestry. More recently it has been used pre-harvest in barely and wheat, mainly for control of certain perennial weeds. Timing of application is important in all these situations. Glyphosate is readily absorbed by leaves and highly mobile in the plant, moving mainly via the symplastic system and probably also in the apoplastic system. Foliar chlorosis followed by necrosis are the most common symptoms. Degradation within the plant is slow. Mammalian toxicity is very low. In the soil it is so strongly absorbed to clay and organic matter that it is unavaliable to plants. Degradation by microorganism can be very rapid or very slow, depending on soil type, but is usually rapid in most agriculture soils (Roberts, 1982).

42 CHAPTER THREE MATERIALS AND METHODS s3.1 Experimental sites The experiments were carried out for two consecutive seasons: 2000/01and 2001/02 at two different sites, Agricultural Research Farm located at Takroof (North sawagi) and a private farm for growing banana at (South sawagi) in Kassala State (longitude 36 23E and latitude N). The soil in both sites was of the silty loam with 30% loam and 70% silt with a ph of Land preparation The experimental sites ( half fedan each) were ploughed harrowed and then leveled. They were divided into 40 plots 3X7m. In each plot two suckers were planted at a spacing of 3x3 m in a hole 60x30x30cm and covered immediately after planting with the top soil. One meter between each two plots was left as a guard row to avoid wind drift. The experiments in both sites were laid out in accordance to the Randomized Complete Block Design (RCBD) with four replicates. Each block contained ten herbicidal treatments including hand weeded plot and a weedy check Planting Materials The planting materials of the local banana cultivar Dwarf Cavendish were used. The selected plant were sword suckers, uniform in size and appearance. The suckers were cleaned of any surface contaminants. The number of suckers used were 80 for each experimental site.

43 3.4The herbicides used The herbicides used in this study were 1.Pendimethalin 500 E.C as Stomp : N (1-ethylpropyl)-3,4dimethyl 2,6 dinitrobenzenamine 2.Dichiorfenidim 80 as Diuron: 3(3,4 dichlorophenyl)-1-1dimethyl urea 3.Oxyflurofen 20 as Goal : 2chloro-1-(3ethoxy-4nitro-phenoxy)-4- (trifluoromethyl) benzene Treatments used were as follows: No Treatments Dose L/ha (Product) 1 Stomp Stomp Diuron 1.0 Kg 4 Diuron 2.0 Kg 5 Goal Goal Diuron +Stomp 1.0Kg +1.0L 8 Diuron +Goal 1.0Kg +0.5L 9 Hand-weeded check Weedy control 0.0 All herbicides were applied after planting as pre-emergence spray using Kubota sprayer, with a flood jet nozzle, with an output 330 L/ha at a pressure of 4 bars. Irrigation then followed after herbicides application immediately and continued at intervals of 7-14 days depending on the weather conditions.

44 The hand weedy received a hand hoeing regularly at monthly intervals until harvesting. Since the previous herbicides were intended for the control of annual weeds, some perennials weeds like Cynodon dactylon and Cyperus rotundus dominated the experimental sites. Thus the herbicide Glyphosate was used at a rate of 2.4 L/ha. To avoid phytotoxicity the sprayed banana plants were covered by polyethylene barrier. 3.5Propping Proping was done to prevent plant from falling over due to the heavy weight of the bunch and to protect them from wind damage. Forked poles were placed against the pseudostem on the side were it was leaning over, care was taken that this technique would not damage the bunch Data collection Crop In this experiment growth and yield parameters were measured as follows: (a) Growth parameters 1-Plant height Plant height was defined as the distance from the base of the pseudostem to the point of the petioles of the two youngest leaves. Tape metere was used to determine the increase in height 6 months after planting of the plant crop. 2-Plant girth (diameter)

45 Pseudostem girth was measured 5cm above ground level 6 months after planting using a tape metere. 3-Leaf production The numbers of leaves produced by each banana plants are recorded. Leaves produced were recorded monthly until 6 months from planting. Permanent mark was made on the midrib of the last counted leaf in order to facilitate counting of the new leaves produced. (b) Yield parameters: 1-According to (Bakhiet,1994) banana maturation was determined by measuring the diameter of the outer central finger of the second hand from the top of the bunch at harvesting calibration of between cm using veriner caliper. Harvest bunches are then weighed using spring balance. 2-Number of hands per bunch were counted. 3-Number of fingers per hand designated as number two from the top of the bunch was counted Weeds The degree of weed control was determined by the count of the weeds present onemonth after herbicide application. Total and individual weed species whether broad or narrow-leaved in a metere square quadrate thrown randomly in each plot were recorded. Weed dry weight per square metere was recorded. The numbers of

46 weeds and dry weight were determined for all herbicides treated plots. Drying of weeds was done in an oven at 80c for 72 hours. 3-7 Statistical analysis Data of the two trials were statistically analysed for valid comparison. Analysis of variance (ANOVA) was applied to analyse the effect of herbicide treatments. Mean speration was done by Duncans Multiple Range Test (DMRT) as a post-anova TEST to determine relation ship among different treatments.

47 CHAPTER FOUR RESULTS It worth mentioning that non of the herbicides and their mixture used in this investigation had any negative effect on banana productivity 4.1 Growth parameters Effect of herbicides treatments on banana plant height (cm) In both seasons all herbicides at their different rates and their mixtures and the handweeding treatments had significantly (P< 0.05) increased banana plant height as compared to the weedy chek. Seperation of means of averages in the two seasons revealed that R2 of Goal 71.36cm was comparable to handweeding cm while R2 of Diuron 81.07cm was significantly higher than handweeding. The above result is confirmed by the average of the two seasons (Table 1) Effect of herbicides on banana pseudostem girth As presented in table 2 in both seasons all herbicides treatments and their mixtures had significantly (P 0.05) increased banana pseudostem girth as compared to the control. However manual weeding gave pseudostem girth which was comparable to that given by either each of herbicides and their mixture in both seasons. In the average of the two seasons Diuron (2.0Kg) was significantly (P 0.05) gave greater increase in the diameter of pseudostem girth (44.66cm) over all herbicides treatments and handweeding as compared to the

48 control (18.62cm) while R2 of Goal (36.62cm) was comparable to handweeding (35.25cm). Table 1 Effect of herbicides treatment on plant height (6MAP) in seasons 2000\ \02 and average in the two seasons Treatments Plant height (cm) Average of the two 2000/ /02 seasons Stomp R abc bcd e R ab abc c Diuron R abc bc d R a a a Goal R bc cd f R ab ab b DiuronR1+StompR abc bc d DiuronR1+GoalR abc bcd e Handweeding ab ab b Control c d g MAP = Months after planting Means followed by the same letter(s) are not significantly different at P<0.05 using Dancan s Multible Range Test. R1= Low rate R2= High rate

49 in the two Table (2): Effect of herbicide treatments on pseudostem girth of banana plant crop (6MAP) seasons 2000/01 and 2001/02 and average in seasons. Treatments Pseudostem girth (cm) Average of the 2000/ /02 two seasons Stomp R b b c R ab b c Diuron R ab b c R a a a Goal R b b f R ab ab b DiuronR1+StompR b b cd DiuronR1+GoalR b b de Handweeding ab ab b Control c c g MAP= Months after planting Means followed by the same letter(s) are not significantly different at P<0.05 using Duncan s Multiple Range Test. R1= Low rate R2= High rate

50 4.1.3 Effect of herbicides on number of leaves This parameter is measured at monthly intervals for six months after planting. Five months from planting no significant effects of either of the herbicides and their treatments and handweeding as compared to control on number of leaves of banana plant crop. After six months from planting results showed that in both seasons all rates of herbicides used in this investigation and their mixtures and the handweeding treatments had significantly (P 0.05) increased the number of leaves of banana plant crop as compared to control. This is also true in the average of the two seasons. R2 of Goal was comparable to the handweeding 18.0 and respectively while R2 diuron gave significantly higher number of leaves per plant than handweeding (Table 3). 4.2 Yield parameters Effect of herbicides treatments on banana bunch weight (Kg) Table (4). showed that all herbicides treatments and their mixtures and the handweeding treatments gave significant (P 0.05) banana bunch weight which was greater than the weedy chek. However, in both seasons Diuron (2Kg) significantly increased banana bunch weight over other herbicidal

51 treatments and handweeding as compared to the control. Moreover, the combine analysis of the two seasons indicated that Diuron (2Kg) was significantly (P<0.05) the best treatment with respect to bunch weights (Kg). Table.3 Effect of herbicides on number of leaves (6MAP) in seasons 2000/01 and 2001/02 and average of the two seasons Treatments Number of leaves (6MAP) Average of the two Stomp 2000/ /02 seasons R b d e R2 17,50 b bc c Diuron R b bc c R a a a Goal R b d e R ab b b DiuronR1+StompR! b c d DiuronR1+GoalR b c e Handweeding ab b b Control c e f M.A.P= Months after planting Means followed by the same letter(s) are not

52 significantly different at (P<0.05) using Duncan s Multiple Range Test. R1= Low rate R2= High rate

53 seasons Table 4. Effect of herbicides treatments on banana bunch weight (Kg) in seasons 2000/01 and 2001/02 and average of the two Treatments Bunch weight (Kg) Average of the 2000/ /02 two seasons Stomp R b c c R b c b Diuron R b c c R a a a Goal R b c c R b b b DiuronR1+StompR b c c DiuronR1+GoalR b c c Handweeding b b b Control c e d

54 Means followed by the same letter(s) are not significantly different at (P<0.05) a according to Duncan s Multiple Range Test. R1= Low rate R2= High rate Effects of herbicides treatments on number of hands per bunch In both seasons herbicides at their different rates and their mixtures and the handweeding treatments had significantly (P 0.05) increased number of hands per bunch as compared to the control. Moreover, the average of the two seasons followed similar treatments. However Diuron (2Kg) in both seasons and the average of the two seasons gave significantly (P 0.05) greater increase in number of hands per bunch over all other herbicidal treatments and handweeding treatment as compared to control (Table. 5) Effect of herbicide treatments on number of fingers per hand In the first season all herbicides at their different rates and their mixtures had significantly (P 0.05) increased number of fingers per hand as compared to weedy chek. Diuron (2Kg) had significantly (P 0.05)

55 resulted in the highest number of fingers per hand as compaerd to other herbicidal treatments and the handweeded control. In the second season with the exception of Stomp and Goal at their low rates all other herbicids treatments and the handweeding had significantly (P 0.05) increased the above-mentioned parameters as compared to the control (Table.6). Results were further illustrated by the average of the two seasons.

56 Table 5 Effects of herbicides treatments on number of hands per bunch in seasons 2000/01 and 2001/02 and average of the two seasons Treatments Number of hands/bunch Average of the 2000/ /02 two seasons Stomp R b 8.12 c 7.39 de R b 8.37 c 7.68 c Diuron R b 8.37 c 7.68 c R a 9.12 a 8.72 a Goal R b 8.12 c 7.31 e R b 8.87 b 8.27 b DiuronR1+StompR b 8.37 c 7.60 cd DiuronR1+GoalR b 8.37 c 7.60 cd Handweeding 6.67 b 8.87 b 8.27 b Control 5.00 c 6.87 d 5.93 f Means followed by the same letter (s) are not significantly

57 different at (P 0.05) according to Duncan s Multiple Range Test. R1= Low rate R2= High rate Table 6. Effect of herbicides treatments on number of fingers per hand in seasons 2000/01 and 2001/02 and average of the two seasons. Treatments No of fingers per hand Average of the 2000/ /02 two seasons Stomp R b bc e R b b cd Diuron R b b d R a a a Goal R b c c R b b b DiuronR1+StompR b b d DiuronR1+GoalR b b d Handweeding b b b

58 Control c c f Means followed by the same letter (s) are not significantly different at (P 0.05) according to Duncan s Multiple Range Test. R1= Low rate R2= High rate 4.3 effect of herbicides on weeds The perdominat weed species found in the experimental sitess were presented in table Effect of herbicide treatments on weed control Data presented in table 7 showed that in both seasons and in the average of the two seasons all herbicides at their different rates and their mixtures had significantly (P 0.05) resulted in an effective weed control as compared to the control, as expersed with percentage weed control. R2 of Diuron in both seasons and in the average of the two seasons was the best treatment that resulted in effective weed control compared to the control. Some weed species in the experimental sites such as Datura innoxia Mill, Argmone mexicana L and Amaranthus viridis L were not effectively controlled with the used herbicides Effect of herbicide treatments on weed biomass g/m 2