Development of the CRI Rootstock Seed Farm

This background, as well as the development of the HLB/ACP Action Plan in SA, led to the strategic decision to develop a citrus rootstock seed farm outside the 5 km buffer zone. Criteria for a suitable farm were at least 10 ha of soil and water suitable for citrus production, and to be located in a safe area within comfortable commuting distance from the CFB. A suitable property was finally found in the Kouga district of the Eastern Cape, near Thornhill, 50 km by road from the CFB. This 232-ha portion of the farm, Cypherfontein, is surrounded by the Longmore state forest and natural vegetation, and a mixed farming (vegetables, flowers, and cattle) neighbour. The nearest citrus orchards in the Loerie valley are >2 km away. The farm was purchased by the Citrus Research Trust and transfer went through on 7 September 2022, whereafter development started.

As its name suggests, Cypherfontein has an abundance of surface water and because of the mean annual rainfall of 800 mm the five earth dams are usually filled. Three boreholes were sunk, two of which will be equipped to supplement the surface water for irrigation of the planned 10 ha planting.
Initial soil classification, done by Coenraad Fraenkel from CRI, revealed Tukulu and Westleigh soil types. During soil preparation an unforeseen layer of mud-rock was unearthed in one section of the planned 10 ha. This required removal of the big rock boulders with earth moving equipment. Prepared soil was ridged, and irrigation installed in five blocks comprising a total of 10 ha. A new store was built together with a pump room fitted with a computer-controlled irrigation system (Fig. 2).

In September and October 2023, 4 659 trees were planted (Figs. 3, 4 and 5), which should yield approximately 7 000 of rootstock seed based on historic averages (Table 1). All trees were made on X639 rootstock at the CFB. Currently, there is space for another 700 trees where new experimental varieties or promising new rootstocks can be established.

The area surrounding the Seed Farm is in a high fire risk area. CRI has joined the Sarah Baartman West Fire Protection Association and works closely with the neighbouring MTO Longmore Forestry company and other neighbours to manage the fire risk. An ongoing strategy is to remove the invasive blue gum and black wattle on large tracts of the farm to prevent fires, restore natural vegetation and open water catchment areas.

CIS Nursery Advisor Michael Nell and his family have settled into the newly renovated farmhouse from where he can assist with general management. The CIS team looks forward to the first harvest in three to five years. During this time, the rootstock trees at the CFB will be gradually phased out. Once concluded, the CIS budwood sources in insect-secure structures should be the only citrus trees within the >8000 ha citrus-free buffer zone, which will make the CFB the safest place to grow budwood in SA.