Development of an appropriate weed management system for the Skeldon Expansion Project, Guyana Sugar Corporation. N. A. Phoenix and D. P.

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1 Development of an appropriate weed management system for the Skeldon Expansion Project, Guyana Sugar Corporation N. A. Phoenix and D. P. Bishundial Guyana Sugar Corporation Inc, Ogle Estate Abstract The decision to expand and modernize the Guyana Sugar Industry brought new challenges to the cultivation of lands using different methods of land leveling, land preparation, field layout, irrigation methods, herbicide application and harvesting, meant new cost- effective techniques had to be adopted. In weed management this meant development of an appropriate low cost sustainable system. This paper examines the methods of weed control done over the past four years and make recommendations for low cost-effective and sustainable weed management. A timely weed control system has been developed to control these weeds, with emphasis on control of (Echinochloa colona and Thallia geniculata) which are competitive and difficult to control. Keywords: Cost effective, weed management, expansion project Introduction The Guyana Sugar Corporation Ltd has embarked on a massive expansion programme to modernise the industry by building a new factory with a capacity of over 350 tonnes cane per hour and at the same time makes it competitive and sustainable. The survival of the industry depends on the cost of production and it has been envisaged that all aspects of production should have reduced costs. Current traditional weed control at Skeldon is equivalent to (3.6%) of the field budget and this will have to be reduced to a lower percent which is necessary for the survival of the industry. This paper examines the weed control strategies used over the past four years and aims to develop a new sustainable system that will be employed in the new expansion areas. The new expansion area is different in many ways from the traditional area, as some of these lands were previously cultivated with other crops such as soybean and rice, which were temporary abandoned for years, while others were pasture savannah and heavy forested lands. As a result of previous activities and different agronomical practices which impact on present weed population, any effective weed management programme will have to recognize these historical conditions and make the appropriate changes to the traditional one. A comparison of the two field layouts is shown in Figures 9 and 9a. 1

2 History and development of the Expansion area The Skeldon Expansion area consists of Blocks one to four and Block ten +. About 50 % of Block one was previously cultivated with various crops such as corn, soybean and rice before the area was temporarily abandoned and used as cattle pasture for years. The remaining 50 % of Block one consisted of pasture, and savannah and heavy forest. Blocks two to four are mainly forest with patches of pasturelands, while block ten plus is basically savannah lands used as pasture. The lands are relatively flat and prior to digging of internal drainage canals these lands remained inundated during the two wet seasons (May June) and (December). This trend is still experienced in blocks three to four and block ten plus. This situation will alleviate itself, as the individual fields are prepared. Block one is fully prepared and partially planted during the period Figure 8 During 2000 to 2003 the Estate tried different chemical weed control techniques to counteract the heavy proliferation of weeds within the expansion and such evaluation will continue until a proper sustainable management system is achieved. The current weed spectrum is shown in Table 4. Materials and methods 1. Pre plant incorporated Treflan (Trifluralin) was incorporated within the depths of 0-18 cm at final harrowing. A rate of 5.5 liters/ha was applied using a 600-liter boom sprayer mounted on a 100-horse power John Deer tractor. The boom sprayer was calibrated at 10 liter/ha at 237kPa ( 35 psi) which was operated by a P.T.O Pressure pump. The swath width of the boom sprayer was five metres. Fan nozzles were used on the boom sprayer. 2. Pre emergent application The treatments Merlin was applied between three to eight days after planting at a rate of kg/ha using CP3 knapsack sprayer at 100pKa (15 psi) and walking speed of 1 metre/ second or by Thrush Commander/ Turbine aircraft fitted with Micronair AU5000 atomisers. The application rates of spray solution using CPC knapsack sprayers were 106 liter/ha and by air craft 16 litre/ha. 3. Pre early post emergent application. The products used at this stage were Merlin + Diuron (0.165 kg) ha or Diuron + 2,4-D (1.1kg + 2.8lt) ha Treatments were applied at eight to 16 days after planting manually or by aircraft. Spray solution rates were 106 lt/ha and 16lt/ha for the former and later respectively. 2

3 4. Medium post-emergent application. The products used when weeds were approximately 15cm tall/long were Dual + Igran at lt/ ha, Asulox + Grandstand at 3.3 kg l/ ha, and Asulox (3.3 kg) ha, and 2,4-D (2.8 l) ha. Treatments were done at days after planting manually using CP3 Knapsack sprayers equipped with AN 2.5 nozzles. The spray volume was 16 l/ha. Asulox and Grandstand were used when there is a mixture of grasses and vines. Dual + Igran or Asulox were used in fields proliferated with grasses. 2,4-D Amine was used when broadleaf weeds including vines were present. Results and discussion Treatment and efficacy The most dominant weeds in the expansion project were Echinochloa colona (Jungle rice) and Thallia geniculata (Wild starch). Plates 4 and 5. Timing and number of applications varied and was based on the intensities of weed proliferation as the crop progressed. The seed bank in the cultivated area was anticipitated to be very high in the plant crop cycle since weeds were maturing and shedding seeds long before the lands were cultivated with sugarcane. 1. Pre-plant incorporated Fields treated with Treflan gave poor results when compared to untreated fields. There were no apparent difference in the proliferation of weeds, (Echinochloa colona (Jungle rice) and Thallia geniculata (Wild starch). This may be due to the reduced efficacy and the use of a higher rate of the product. There was also a problem to incorporate the Treflan in the top cm of the soil with the current implements which can cause too much dilution of the product and therefore a sub-lethal dose and poor control. This treatment was discontinued. 2. Pre-emergent Merlin (Isoxaflutole) applied alone as a pre- emergent treatment on fields with little or no weed emergence gave very poor results. This was observed at three days after application. At six days after application, a few of the emerged weeds were bleached indicating that the Merlin had an effect on the grass weeds. Plate 1. At nine days after application, the entire fields were heavily infested with mainly jungle rice. Plate 3: This was most likely due to the heavy weed seed bank in these fields and ideal conditions for germination. 3

4 3. Pre early post-emergent application The choice of treatments for pre-early post emergent application was dependent on the proliferated ratio of true grasses and broadleaf weeds. A heavy proliferated field with Echinochloa colonum (Jungle rice) against Thallia geniculata (the two dominant weed in the expansion) will require an application of Merlin + Diuron, while heavy proliferation of Thallia geniculata and few spots of Echinochloa colonum will require Diuron + 2,4-D as the preferred choice. The level of weed control that was achieved with Merlin plus Diuron was excellent as seen in Plate 2. In an evaluation to compare the efficacy of the standard treatment, an untreated control strip was left. The results indicated that the treatment is very effective as shown in Plate 4. The length of control sometimes last from seven to eight weeks depending on the weather condition. In wet condition control may only last up to four weeks after application. 4. Medium- post emergent application. The amount of medium-post emergent application varied between one and four treatments depending on the frequency with which weeds proliferated the fields. Plate 8. The choice of herbicide was dependent on the type of weeds present. Igran + Dual gold and Asulox gave good control of Echinochloa colona at the medium post-emergent stage. However, Asulox gave better control when the weeds were older when compared to Igran + Dual gold. The tank mixture of Igran + Dual gold was usually the preferred choice since the cost per unit area was less. The use of 2,4-D Amine controlled relatively all broadleaf weeds found in the expansion area. Control of weed species seen in Plates 7,8, 9,10, and 11 were very good. Grandstand also showed good control of the weeds seen in Plates 6, 7, 8, 9, 10, and 11 at medium post- emergent stage. Cost per hectare Results obtained during the period clearly showed that cost/ hectare reduced by 67 percent from plants to 3 rd ratoon. This is an indication that the seed bank was being reduced in subsequent cycles thus reducing the number of treatments required to control weeds.(see figure 1) 4

5 Fig 1:Total Cost as per Cycle ($US) Fig 2: Effects of timing of Pre-arly post Emergent application on Plant cane yields Cost/ha Pl 1R 2R 3R Cycle cost/ha ($US) Yields(TC/H) Sec4 8DAP Sec3 9DAP Sec5 12DAP Sec7 12DAP Sec6 14DAP Days after planting Sec8 14DAP Sec2 16DAP Sec 9 19DAP DAP Pre early post treatments done between eight and nineteen days after planting has little or no effect on yield (see figure 2). The cost per hectare for both plants canes treated between 8-21 days after planting in the pre-emergent stage and between days after planting in the medium postemergent stage increased and then decreased. This variation was due to the weed stage and type of treatments. Figs 3a and 3b. Fig 3a: Ratoons Yields vs pre- early Post days after harvest Fig 3b: CPU per cycle as per year ($US) The ratoon yields were not affected by the timing of the pre- to early post-emergent treatments, which ranged from 11 to 26 days after reaping. Figure 4 5

6 Fig 4: Ratoons Yields vs pre- early Fig 5: CPU per cycle as per year ($US) 120 " Cost/Ha Year PL 1R 2R 3R Post treatment-days after harvest The control of weeds in plant canes cost more than in ratoons. Figure 5. Tables 3a, 3b and 3c. Cost per hectare and the number of treatments did not have any effect on yields. The cost increased almost proportionally with the number of treatments. See figures 6a and 6b. Tables 1 and 2. Fig 6a: No of treatments vs CPU and Yield -Plants Fig 6b No of treatments vs CPU and Yield -Ratoons TCH/Costper ha Treatments Cost/HA TCH Treatments TCH/Cost per HA Treatments Cost/HA TCH Treatments Years Years 0 The cost per hectare in ratoon canes in the Expansion area was lower in 2002 and 2003 but higher in 2001 when compared to the Traditional system. The reasons being the higher number and type of treatments that were under evaluation at that time(2001) and secondly there was most likely a reduction in the seed bank thus reducing the amount of treatments required for good control. See figures 7a, 7b and 7c. 6

7 Fig 7a Cost /ha- traditional v/s cost/ha - Fig 7b Cost /ha- traditional v/s expansion for 2001 cost/ha- expansion for 2002 # % #( ' # $% & ' Fig 7c: Cost /ha -traditional v/s cost/ha -expansion for 2001 # $% & ' 7

8 Recommendations and conclusion The following recommendations are based on recent experiences and would most likely undergo changes based on conditions, weed succession and discovery of better products and techniques. Plants Pre-early post application 100 % Pre-early post application should be done on all plant canes by aircraft since the application is uniform and cheaper. The treatments are a) Merlin + Diuron applied at a rate of (0.165kg + 1.1kg)/ha at two weeks post planting or b) Dual + Igran applied at a rate of (0.62lt + 2lt)/ha at four weeks post planting Post-emergent application Post-emergent treatments should be between % of planted hectarage A trailing or mounted tractor boom sprayer should be used to apply one of the following treatments: - a) Igran + 2,4-D applied at a rate of (2.0lt +2.8lt)/ha at 8-14 weeks post planting or b) Asulox + 2,4- D applied at a rate of (3.3kg +2.8lt)/ha at 8-14 weeks post planting. Ratoons Pre-early post application 75% Pre to early post-emergent application should be done on all ratoon canes by aircraft and the remaining 25% (no fly zones) should be done by Trailing or mounted tractor boom sprayer. The preferred treatment should be Dual + Igran at a rate of (0.62lt + 2lt)/ha at 2-4 weeks post harvest. Medium post application A mounted tractor boom sprayer should do medium post -application in 25% of the harvested hectarage. Igran + 2,4-D at a rate of (2.0lt +2.8lt)/ha should be applied at 8-10 weeks post harvest. To get the best results it is recommended that - No hand weeding or manual chemical weed control should be practiced in the expansion. The early post- emergent treatments should be applied when the weeds are 15 cm tall. The best treatments should be a combination/tank mixture of a pre- and an early postemergent treatment. Application should be done with the aircraft and/or tractor boom sprayer. It can be concluded that the experiences gained in managing weeds during the past four years will enable a cost- effective, sustainable and appropriate weed management system for the remainder of the expansion project. 8

9 PLATES: Appendix Excellent control bleached )*$+,-* %./ %0* %1 2% & 3 %%04.5/ 6%& 3 Echinocloa Colonaearlly-post )*$-3 ' %% * %12% Excellent control Untreated control -poor )*$, )* % %& 3 %%0%& 3 % )*$, 7%0% 3 * %12%3 Early post stage 9

10 Plate 5: Main weed Echinochloa colonum Plate 6: Thallia geniculata (wild starch) main weed in some fields Plate7: Physalis angulata (Popo) (found on spots in field) in canes Plate8: Ipomea spp entangled Plate : Main weed Echinochloa colonum Late stage Plate 9: Heliotropium spp (white lady) (spots in field) Plate 10: Canna indica (wild canna) (on surrounding dams) indica (dams) Plate 11: Ipomea spp and Canna 10

11 TABLES Table 1: No of Treatments and Cost in plant canes $ US ( %./ ' # " $% " & - & $ ) " $ ), $ ) $ ) $ ) $ ) + $ ) $ )* $ ) $ )* $ )* $ ) * $ )* $ ) * $ )* $ ) $ ) 11

12 Table 2: No of Treatments and Cost in ratoon canes $ US ( %./ ' # 0 1 " $% " & - & ) $") $ ) $ ) $ ) $ ) $ ) $") $ ) $ ) $ ) $ $ ) $ ) * $ ) $ ) 12

13 Table3a: Yield as per Cycle 2001 to Sec Fld Ha Cycle Actual Actual TCH TC/TS TSH cane sugar Pl Pl Table 3b 2002 Sec Fld Ha Cycle Actual Actual TCH TC/TS TSH cane sugar R PL R PL PL PL Table 3c 2003 Sec Fld Ha Cycle Actual Actual TCH TC/TS TSH cane sugar R R R R PL PL

14 Table 4: Weeds at Manarabisi Expansion Before Cultivation After Cultivation Ischaemum rugosum (Muraina grass) Echinochloa colonum (Jungle rice) * Canna indica (Wild cana) Brachiaria mutica (Para grass) Cordia macrostachya (Jacq) R&S (Black sage) Cynodon dactylon (L) Pers. (Bahama grass) + Sphenoclea zeylanica Gaertn (Soap bush) Physalis angulata (Popo) Mikania micrantha H.B.K. (Bitter talli vine) Ipomea tiliacea (Wild potato) Momordica charantia (Wild carilla) Canna indica (Wild canna) Heliconia sp (Wild ginger) Heliotropium spp (White lady) Solanum stramoniifolium (Buro- buro) Emilia sonchifolia (Grease brush) Azolla sp (Bissi-bissi) Thallia geniculata (Wild starch) * Momordica charantia (Wild carilla) Portulaca oleracea (Hog calaloo) Phaseolus schotti Benth (Port Mourant vine) Vigna luteola (P- vine) NB: * Main weed found in cultivated fields. + Main weed found on surrounding dams. All other weeds are found in limited numbers within the new expansion. 14

15 Fig 8: Map of Existing Cultivation & Expansion 15

16 BLOCK SYMBOL SECTION HECTARE BLOCK ONE A BLOCK TWO B NOT COMPLETED 850 BLOCK THREE C NOT COMPLETED 850 BLOCK FOUR D NOT COMPLETED 690 BLOCK TEN + E NOT COMPLETED 1530 Total

17 Figure 9 a: Diagrammatic representation of two fields at MRP Expansion Secondary Middle walk Dam 12 Inch Tube 12 Inch Tube Collector drain Dam Field A Direction of row High point dam Field B Direction of row Gradient (1 in 500) Gradient 1 in 500 Dam Collector drain Dam 24 Inch Tube Side Line 24 Inch Tube Fig 9b: Diagrammatic representation of two Traditional fields (Dutch Beds) D/B Middle walk D/B Field A Field B C/C D/B F\F D/B Cross canal D/B F\F D/B C/C D/B D/B 17