Weed Management in Horticultural Crops

TEMPERATE FRUIT CROPS

I. Apple: Apple (Malus domestica Borkh) grows mostly in the temperate regions of Jammu & Kashmir, Himachal Pradesh and Uttrakhandand and to small extent in Nilgiris Hills of Tamil Nadu. Rosa moschata, Rosa eglantaria, Rubus spp. and Berberis spp. are some of the predominant weeds of apple orchards.

Control:

1. Mulching: In newly established trees, the need for weed control is greater and that use of black polythene mulch proved just as effective as good chemical treatments. Increase in yield upto 40 per cent was also realized in apple under this treatment.
2. Intercrops: Growing intercrops in rows between the trees and in the basins of apple trees to suppress weeds and to supplement the income is very common in India. The intercrops grown are mustard (oil yielding), wheat, oat and, to some extent, barley. Mulching with black polythene and oat leaves in apple basins indicated that oak leaves were the best for suppressing weeds.
3. Chemical control: Rosa rubignosa and Berberis sp. can be controlled with the spray of gramoxone at 500 ppm + Ansar 529 at 1000 ppm when applied as post-emergent spray. Gramoxone (3.75 kg/ha) was found to be the most efficient post- emergent herbicides out of a number of herbicides tested in apple orchards. And also in apple orchards, found that an application of Aminotriazole (5.0 kg/ha) and Simazine (5.0 kg/ha) as pre-emergent spray resulted in the elimination of broad leaf weeds and increases in the density of grasses. The diuron at 2.0 kg/ha and nitrofen at 5.0 kg/ha to be highly effective and economical in controlling Oxalis latifolia. Simazine at 1.0-2.0 kg, nitrofen at 0.5-1.0 kg and Diuron 0.8 kg/ha to be very effective for controlling weeds in apple nursery which resulted in increased number of saleable grafts. Weed control in non-bearing apple orchards with Diuron at 5.0 kg/ha applied as pre-emergent treatment or Dalapon at 8.0 kg/ha applied as pre-emergent treatment.

II. Peach: A suitable cover or green manure crop may be sown in rainy season after the fruits are picked and ploughed–under during winter. Peach trees growing in straw mulched strips, 3 m wide, grew at a faster rate than the control under permanent pasture and produced twice as many fruits of larger size in their fourth and fifth seasons.

Control

1. Mechanical methods: Ploughing of whole orchard with bullock drawn implement or motor run implement is also the best for controlling weeds in peach orchards.
2. Intercropping: Intercropping peach orchards with mung, pea and onion reduced the density of weeds both in basins and inter-rows.
3. Chemical control: Gramoxone at 500 ppm, mixture or 2,4,5-T at 100 ppm and Gramoxone at 500 ppm controlled the shrubby weeds of Rosa moschata, Rubus sp. and Berberis sp. effectively. Weed control in peach orchards with the combination of dalapon at 10 kg/ha and 2,4-D at 1.0 kg/ha when applied in two split doses. The residues brought about significant suppression of weeds in the next season also. Weed control with terbacil at 3.0 and 4.0 kg/ha. Commelina nudifera, Ageratum conyzoides and Euphorbia hirta were controlled well by 5.0 kg/ha Simazine and 3-5 kg/ha Atrazine.

III. Apricot: Cultivation by bullock drawn implements or motor run implements and cover cropping the inter-rows with mustard and wheat to reduce the density of weed population is very common.

Control:

1. Chemical control: In apricot chemical weed control, Simazine or Diuron at 2.0, 4.0 and 6.0 kg/ha checked the emergence of grasses and broad leaf weeds for 90 days. Best control was achieved with 4.0 and 6.0 kg/ha Simazine.

IV. Plum: Chemical weed control provides an excellent opportunity in keeping the plum plantations free from undesirable vegetation and improving the health of of trees resulting in higher productivity. Hand weeding is to be superior to herbicides application. Simazine, diuron and bromacil singly at 5.0-7.5 kg/ha and terbacil at 3.0-4.0 kg/ha got effective weed control in old trees of plums. Excellent control of weeds can be achieved in plum orchards with simazine at 5.0 kg/ha.

V. Pear: Herbicides in pear orchards that krenite (fosamine) at 15-30 l/ha with 5-10 per cent regrowth after one year comparable that on plots treated with 2, 4, 5-T at 1.0 litre in 400 litres of water per hectare. Fosamine affected much more than 2, 4, 5-T.

VI. Strawberry, raspberry and blue berry: The cultivated varieties of strawberry (Fragaria spp.) grown in India are all imported. The land is prepared by ploughing deep followed by harrowing. Bulky organic manures are added. The weeds are controlled by light hoeing as land when the runners form. When plants blossom in spring, straw is used to bed the plantation to keep the fruits off the soil. After fruiting, straw and weeds are removed, and all runners are cut off. Hoeing is continued. Strawberry is rotated with vegetables every three years to reduce the density of weeds. Opaque plastic mulch suppressed weeds, conserved soil moisture, increased soil temperature in cool weather and reduced them in warm weather and increased the yields in strawberry. Black polythene mulch controlled annual weeds well but not perennial weeds like Agropyron repens and Oxalis spp. Annual weeds germinating after planting strawberry in late March had no effect on crop growth if removed by late May. Dense weed cover thereafter severely inhibited stolon growth, virtually eliminating it if allowed to remain beyond mid -august. 8.0 lb/acre DCPA with 4.0 lb/acre chloroxuron or 4.0 lb/acre diphenamid effectively controlled important weeds like Cyperus compressus, Digitaria ciliaris and Eleusine indica in strawberry.