Dieback Resistance Potential in Different Varieties of Shisham (Dalbergia sissoo Roxb.)

Nine phenotypically different varieties of Shisham (Dalbergia sissoo Roxb.) were identified from Punjab University, Quaid-e-Azam Lahore, Pakistan and adjacent areas, on the basis of physical appearance of the plant, branching pattern, pod characters, leaf and leaflet size and shape, branching and leaf density and stem surface characteristics. On the basis of their relative resistance to dieback disease, the different varieties were named as Resistant 1, Susceptible 1‑4, Unspecified 1‑4. The Resistant 1 variety is characterized with dense, and long branches, which grow outward and downward forming a canopy. Generally plants do not attain much height. Leaves are large up to 16 cm in length, with four or five leaflets per leaf. Leaflets broad, globose or subglobose, young leaflets glaucous, mature leaflets glabrous, leaflet apex apiculate. Pods small, generally one rarely two seeded. Susceptible 1 and Susceptible 2 varieties were found to be highly susceptible to dieback showing 20% or more dieback incidence. These two varieties have been commonly cultivated in Punjab. Susceptible 3 and Susceptible 4 varieties were least susceptible showing dieback incidence not more than 2 %. The unspecified varieties 1 – 4 were named so because they did not show any disease symptoms but number of plants of these varieties was not large enough to decide their resistant potential. Shisham forestation can be revived by planting Resistant 1 and less susceptible varieties viz., Susceptible 3 and Susceptible 4 on suitable, well-drained sandy loam soils

Extent of Shisham (Dalbergia sissoo Roxb.) Decline in Sialkot, Gujranwala, Lahore and Sargodha Districts

A thorough survey of four districts of Punjab viz. Sialkot, Gujranwala, Lahore and Sargodha was carried out during May-June 2003 to study the present scenario of shisham (Dalbergia sissoo Roxb.) decline in these areas and to find out relationship, if any, between disease severity and edaphic conditions. From each of the four districts, canal banks, highways and roadsides, and agricultural lands were surveyed. In Lahore surveyed areas also included University of the Punjab, Aitchison College and roadside along the canal bank of BRB Lahore Branch. From each district 700 – 1200 plants were observed. Shisham trees were found to be attacked with two types of diseases viz. wilting and dieback, the latter being the more prevalent than the former. Maximum mortality of 75 – 80 % was observed along the canal banks except BRB Lahore branch. Along the highways and roadsides 20 – 40 % plants were found dead. In the Punjab University about 10 % plants were found dead while 17 % were affected with dieback and wilting ranging from mild infection to highly diseased. The least disease incidence and mortality rate was observed on plants growing on agricultural lands, along the roadside of BRB Lahore branch and in Aitchison College. Disease incidence and severity seemed to have no relation with soil pH. Generally older plants were found to be more susceptible to the disease attack than the younger ones. It was concluded that plant resistance to disease attack was associated with proper irrigation management. Apparently stressed conditions especially high soil moisture content is responsible for the attack and severity of the disease. It is recommended that along the canal bank shisham should be replaced with Eucalyptus spp. Furthermore, seeds from the resistant shisham plants, standing healthy among the hundreds of dead ones along the canal banks, should be used to raise nurseries for shisham plantation on suitable places away from the canals.&nbsp