Most common weeds of sugarcane in India are Sorghum halepense, Cyperus rotundus, Cnodon dactylon, Digitaria sanguinallis, Eleusine indica, Saccharum spontaneum, Trianthema monogyna, Euphorbia hirta, Eclipta alba, Commelina benghalensis, Digera arvensis, Phyllanthus nirui, etc. If these weeds are not controlled from very beginning the reduction in sugarcane yield may be as high as 10-70%. The most critical period for the week competition in sugarcane is upto 4 months after sowing beyond which the crop smoothers the weed flora by itself.

Control measures. The mechanical methods of weed control include cultural practices, hot weather ploughings, hoeing and weeding, mulching, cropping system etc. that reduce the weed population and increase the sugarcane yield. But these methods are very cumbersive, time taking, expensive and at times it becomes difficult because of non-availability of labour and unfavourable climatic conditions for such operations. Chemical control of weeds offers a good substitute.

List of herbicides used for weed control in sugarcane

Name of the herbicides	Rate of appli-cation a.i.	Time of application			Remarks if any
		Pre-Plant	Pre-emer-Gence	Post-emerg-ence
1. Simazine orAtrazine or	1.5-2 kg/ha	-	3 DAP	-	If 2, 4-D amine is applied At 1 kg/ha at 45
Ametryne, Prometryne, Desmetryne	2.0 kg/ha	-	-do-	-	DAP it gives better result (in addition to simazine)
2. Diuron, Alachlor Or	2.0 kg/ha	-	-do-	-	-do-
Tafazine, Karmex	2.0 kg/ha 1.5 kg	-	-do-	-	-do-

DAP = Days after planting

Tips to ratoon management
Ratoon is a crop, which is allowed to grow in the same field from the roots to the previous crop without planting seed setts a new.

Relative merits and demerits of ratooning

Merits

De merits

Cost of seed, seed bed preparation and planting is saved. Ratoon crop utilizes the residual Fertility of the previous crop. Ratoon crop matures earlier and helps in running sugar mills earlier. Thus the field is vacated earlier for the next crop. The quality of the produce is superior to planted cane. Total cost of cultivation is less as compared to the planted one. The yield remains equal to the planted crop if due care is taken.

Ratoon crop is invariably attacked severely by insects, pests and diseases. Thus the yield is very poor. The soil becomes poor in fertility when ratooning is done for more than 2 years.

Five tips to obtain higher ratoon yields. •     Stubble shaving
•     Drenching with insecticide and fungicide
•     Off-barring
•     Nutrients application
•     Gap-filling

WATER MANAGEMENT
Number of irrigation in sugarcane depends upon the climatic conditions, type of soil, method of sowing and manures and fertilizers. The hot weather associated with dry winds and drought increases the water requirement of the crop. The crop sown in trenches needs relatively less water but sandy soils and application of more fertilizers increase the water uptake. On an average 1 ton cane needs about 60-70 tons of water or thin varieties of cane need 150 cm thick canes and need 200 cm water and Adsali planted canes 200 cm, in addition to 75 cm rainfall. The crop should be irrigated when available water reaches to 50% level.

The soil must have sufficient moisture at the time of sowing. First irrigation should be done when about 20-25% plant have germinated or about 20 days after sowing and the irrigations are given at 10-15 days interval during summer, 25-30 days interval during winter and if there is drought the crop should be irrigated during rainy season also as and when needed. The crop needs maximum water at tillering stage and during elongation or grand growth phase.

Under water logging conditions the root respiration becomes poor. Nutrients are leached down, activities of useful micro-organisms are reduced and the crop lodges down with an excessive branching. Thus the quality becomes poor along with very low crop yield. These all make it necessary to drain the excess water from the field.

Drip Irrigation:

• Planting setts obtained from 6-7 months old healthy nursery and planted in paired row planting system with the spacing of 30x30x30 / 150 cm.
• Eight setts per metre per row have to be planted on either sides of the ridge thus making it as four row planting system.
• 12 mm drip laterals have to be placed in the middle ridge of each furrow with the lateral spacing of 240 cm & 8 ‘Lph’ clog free drippers should be placed with a spacing of 75 cm on the lateral lines. The lateral length should not exceed more than 30-40 m.Phosphorus @ 62.5 kg ha-1 has to be applied as basal a the time of planting.
• Nitrogen and Potassium @ 275:112.5 kg ha-1 have to be injected into the system as urea and muriate of potash by using “Ventury” assembly in 10-12 equal splits starting from 15 to 150-180 days after planting.
• Low or medium in nutrient status soil to be given with 50 per cent additional dose of Nitrogen and Potassium. Irrigation is given once in three days based on the evapo-transpiration demand of the crop.
• The double side planting of sugarcane with lateral spacing of 120+40 cm under subsurface drip fertigation system improves the yield.

Paired row – Drip layout in sugarcane

Concept of fertigation

1. Fertigation is the judicious application of fertilizers by combining with irrigation water.
2. Fertigation can be achieved through fertilizer tank, venturi System, Injector Pump, Non-Electric Proportional Liquid Dispenser (NEPLD) and Automated system
3. Recommended N & K @ of 275 and 112.5 kg. ha-1 may be applied in 14 equal splits with 15 days interval from 15 DAP.
4. 25 kg N and 8 kg K2O per ha per split.
5. Urea and MOP (white potash) fertilisers can be used as N and K sources respectively
6. Fertigation up to 210 DAP can also be recommended

Advantages of Fertigation

1. Ensures a regular flow of water as well as nutrients resulting in increased growth rates for higher yields
2. Offers greater versatility in the timing of the nutrient application to meet specific crop demands
3. Improves availability of nutrients and their uptake by the roots
4. Safer application method which eliminates the danger of burning the plant root system
5. Offers simpler and more convenient application than soil application of fertilizer thus saving time, labour, equipment and energy
6. Improves fertilizer use efficiency
7. Reduction of soil compaction and mechanical damage to the crops
8. Potential reduction of environmental contamination
9. Convenient use of compound and ready-mix nutrient solutions containing also small concentration of micronutrients.
   

Hoeing and Earthing

Both hoeing and earthing are closely associated factors because hoeing is necessary for earthing. The hoeing is done with the help of cultivators and it starts just after one week of sowing (the first hoeing is called as blind hoeing) and second about 3 weeks after sowing and subsequent hoeings after every irrigation.
The objectives of blind hoeing are

1. to break the hard crust at surface, which might create problems to the sprouting seedlings,
2. to cover the exposed setts properly, (3) to uproot the weeds, if any and
3. to replace the damaged setts by diseases or insects.

In the entire crop needs about 4-6 hoeings. The hoeings are necessary for

(i) better aeration,
(ii) preservation of water from evaporation loss,
(iii) better tillering and control of weed, insects, pests and diseases.

The earthing is done:

1. to protect the crop from lodging (as it provides mechanical support to the growing plants),
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2. facilitate irrigation and economise water use efficiency,
3. to control the weed infestation in the field,
4. to control the stem borer
5. to remove the water shoots and
6. to drain out the excess water from the field.

The earthing is automatically done by repeated hoeing in the field. The first earthing is over by the end of May or middle of June in which the field becomes fully levelled and it is left in the same condition till the end of July and further repetition of hoeings results in gathering the soil around the plants which completes the second earthing by the mid of August. Now the ridges are made in the plant-rows and furrows are made in the inter-row space, which is just reverse of the condition at the sowing time.

Drought Management:

• Soak the setts in lime solution (80 kg Kiln lime in 400 lit) for one hour.
• Plant in deep furrows of 30 cm depth.
• Spray potash and urea each at 2.5 per cent during moisture stress period at 15 days interval.
• Spray Kaolin (60 g in 1 ltr. of water) to alleviate the water stress.
• Under water scarcity condition, alternate furrow and skip furrow method is beneficial.
• Apply 125 kg of MOP additionally at 120 day of planting.
• Basal incorporation of coir waste @ 25 tonnes/ha at the time of last ploughing.
• Removal of dry trash at 5th month and leave it as mulch, in the field.