Partial Root Parasite – Striga
1. Witch weed (Striga species) is well known partial root parasite of sugarcane Jawar, maize, cereals and millets in India. There are four species of Striga reports in the country on sugarcane, rice , sorghum and other millets.
2. S. quphrasioldes
2. These plants although obligate parasites do not obtain all of their nutrient material from their host root. They posses’ chlorophyll bearing leaves. Plants are 20-60 CM in roots of cereals, sugarcane, etc.
3. Striga can be found on light as well as heavy soil in rabi and kharif season. The seeds of Striga are very minute and produced in great abundance 50,000 to 1, 00,000 seeds /pl/yr.
4. One flower / capsule contains 1200-1500 seeds. Viability of those seeds has been reported to be from 12-40 years. Short distance dissemination of these seeds.
5. For germination of seeds of Striga species, stimulant provided by the root executes of specific host is essential.
6. Seed starts germination after 7-10 days. In most cases germination occurs 40 cm depth. After germination, the parasites grow below the soil surface for about 4-8 weeks and produces underground stem and root.
7. The underground portion of the stem contains bud in the axil of leaf. Stem of parasite forms haustoria which penetrates the root of hosts plants and also water and nutrient eventually wasting and destroying the host.
Striga Difficult to Control Because:
1. Heavy seed production 50,000 to1, 00,000 per plant.
2. Seed viability is longer.
3. Most hyyries are stimulating positive.
4. Alternative host like grasses are present on bunds.
Control Measures of Striga:
1. Complete eradication of parasite before flowering.
2. Regular Interculture should be followed.
3. Crop rotation with cotton-Jowar- Groundnut.
4. Weedicides are used to control Striga before flowering.
a. 2-4-D @ 2.5 lit/500 lit of H2O per ha.
b. Attrazine @ 2 kg / 500 lit of water per ha.
c. 1% TCPA @ 45 kg/ha.
d. Deep ploughing after harvest reduces the vialibility of seed.