PLANT PROTECTION NEWS In this issue AGRICULTURAL RESEARCH COUNCIL - PLANT HEALTH AND PROTECTION Spring 2020 No 116 Outbreaks of the brown locust, Locustana pardalina, Hidden treasure uncovered in the Rhizobia collection reported from the Karoo Outbreaks of the brown lo- cust, Locustana pardalina, developed in the eastern and south-eastern Karoo in September-October after good early rains induced hatching from overwin- NEW diagnostic seed health test tering egg concentrations. available Some of the early reports were of large-size and highly gregarious hop- per bands, which indicated mass- hatching from overwintering egg beds Outbreak areas in the Karoo that had been laid by the previous gen- eration in March-April 2020. As the ARC predicted, the Quarantine nematode found on garlic hopper bands started to fledge into adults from mid-November 2020. The fledgling swarms then aggregated into large adult swarms that started to migrate by the end of No- vember 2020. Swarms that develop during The brown locust Locustana pardalina New early summer (November-December) book launched in the eastern and south-eastern Karoo typically fly east and north-east on the prevailing winds. During such outbreaks, swarms can readily escape the Karoo and invade the cereal crop producing areas of the Free State Province and North West Province. These swarms can also invade neighbouring Leso- Editorial Committee tho, as they have done in the past. Almie van den Berg (ed.) ● Ian Millar ● Marika van der Merwe Young maize crops will be particularly vulnerable to the locust swarms and severe dam- ● Petro Marais ● Elsa van Niekerk age to crops can be expected if swarms are not controlled. Local house-hold food security General enquiries will be under threat. Plant Protection Research, Private Bag X134, Queenswood, Any swarms developing in the Northern Cape Province (Central Upper Karoo 0121 South Africa and Bushmanland) typically fly north at this time of year and pose an invasion threat to e-mail: [email protected] ● web- site: http://www.arc.agric.za Botswana and Namibia. Any swarms escaping control will rapidly mature and will lay eggs by mid-December. A second genera- tion of hopper bands can be expected by Christmas and into the New Year. The further development of the out- break will be dependent upon the distribution of follow-up rains. Contact: Roger Price at [email protected] NEW Diagnostic Seed Health Test Available Detection of Tomato Brown Rugose Fruit Virus (ToBRFV) using RT-qPCR assay at ARC –PHP Tomato brown rugose fruit virus (ToBRFV), is a newly- emerging seed-borne virus in the genus Tobamovirus. This virus is causing severe losses within tomato and pepper crops globally. Ma- jor symptoms include a mosaic pattern on the leaves, distortion of leaves and brown and/or wrinkly spots on fruits. Due to the poten- tial economic impact of this virus, it is essential that planting materi- al be certified free from this virus, for trade purposes. The Taqman RT-qPCR assay, as described in the International Seed Federation (ISF March 2020), was optimized, and is now readily available at ARC-PHP Virology Laboratory, which is registered with DALRRD. Test results will be available within two weeks after re- TBRFV: symptoms of tomato fruits (A) and leaves (B) (https://www.freshplaza.com/article/9099991/italians- ceipt of samples. Standard terms and conditions apply. share-knowledge-on-tomato-brown-rugose-fruit-virus- tobrfv/) Contact: Team Manager, Dr. Elna van Der Linde at [email protected], or Virologists: Ms Marika van der Merwe at [email protected] or Ms Nicola Robbertse at [email protected] PHP hosts the FAO and DALRRD to hand over equipment for control of fall armyworm The ARC – Plant Health and Protection hosted an equipment handover function for the Food and Agricultural Organisation of the United Nations (FAO) and the Depart- ment of Agricultural, Land Reform and Rural Development (DALRRD) on 31 August 2020. The small function was held outside at the ARC-PHP campus. The equipment that was handed over will be used in the country’s fight against the fall armyworm (FAW). It ranged from cell phones for use of the FAO FAW Monitoring and Early Warning System (FAMWES) app, to traps to help monitor the movement of this pest on the ground. Equipment was shared between the various provinces and the ARC. As part of the FAO Farmer Field School, which is being implemented by the ARC in the Limpopo and Mpumalanga provinces, this equipment will be used by female and youthful small-holder farmers to monitor FAW in their communities. FAO and DALRRD equipment handover function hosted by PHP Contact: Robin Lyle at [email protected] 2 PLANT PROTECTION NEWS © Information may be used freely with acknowledgement to the source Uncovering the hidden treasure in the Rhizobia Collections The ARC-PHP has established a memorandum of understanding with a local biological products manufacturing company, Victus Bio (Pty) Ltd. towards screening and development of rhizobium as commer- cial inoculants for the cultivation of economically important legumes. As part of this agreement, strains of Bradyrhizobium spp. from the rhizobium collection of PHP (SARCC) were screened for nodulation and nitro- gen fixation efficiency in soybean (Glycine max L.) under different conditions. The first phase of this trial involved the screening of 25 Bradyrhizobium strains. The results indicated that there are a number of Bradyrhi- zobium strains, currently deposited in the SARCC collection, which are specific to soybean nodulation and that result in significant nodulation and nitrogen fixation efficiency compared with the industry standard cur- rently being used in the country. The first strains will be tested under field conditions during the 2020-21 sea- son. Contact: Ahmed Hassen at [email protected] Rhizobium screening trial on nodulation and nitrogen fixation of soybean using 25 strains of rhizobia from the rhizobium collection showing initial phase (a and b) and second phase (c) of the glasshouse trial. Entomologist called as expert witness in court case Ms Vivienne Uys, the termite taxonomist at the National Collection of Insects was subpoenaed by the Magistrate’s Court in the District of Rustenburg to testify as an expert witness in support of a plaintiff who had purchased a house severely infested and damaged by termites. The defendant, the seller of the house, had failed to disclose the ter- mite infestation as required by law. The plaintiff sued for compensation for expenses in- curred in repairing the house and ensuring its structural integrity. The Court ruled in favour of the plaintiff following expert testimony provided by the ARC entomologist. The expert testimony was based on a report compiled by Vivienne Uys, following a site inspection of the house. During the site visit, severe termite damage to most of the roof beams was evi- dent, along with characteristic soil deposits, typical of fungus-growing termites (Family:Termitidae; Subfamily: Macrotermitinae). Soil deposits were also found within the electrical box, mounted on an inside wall. It was clear that the damage had been present Termite damage to roof for a considerable amount of time. Ms Uys was questioned on her expertise and experience beams as a termite specialist and gave evidence regarding the identity and life-history of the ter- mites found at the dwelling. Contact: Vivienne Uys at [email protected] 3 PLANT PROTECTION NEWS © Information may be used freely with acknowledgement to the source Identity of quarantine nematode confirmed Dr Antoinette Swart of the National Collection of Nematodes found two female nematodes and a number of juveniles of the genus Ditylenchus in a garlic sample submitted for analysis by DALRRD. Both females were con- specific with the quarantine nematode, Ditylenchus dipsaci. No males were present in the sample, so only female characters could be used to diagnose the species utlilizing the Ditylenchus identification key, which employs mor- phology and morphometrics. According to the Diagnostic Protocol of Regulated Pests (2015), molecular identifica- tion of the species D. dipsaci is required when specimens cannot be distinguished conclusively. Specimens were sub- sequently sent to Dr Ebrahim Shokoohi (University of Limpopo) for molecular identification, which reached him on 24 August 2020. Molecular identification was deemed the best way to confirm the identity of the specimens. The molecular results were received on 21 September 2020 and confirmed that the specimens were D. dipsaci with high similarity of two genes (ITS and 18S rDNA). D. dipsaci lives mostly as an endoparasite in aerial parts of plants (stems, leaves and flowers), but also attacks bulbs, tubers and rhi- zomes. This nematode is seed-borne in Medicago sativa (lucerne/ alfafa), Allium cepa (onion), Trifolium spp. (clovers), Dipsacus spp. (teasel) and Cucumis melo (melon). Of great importance is the fact that the fourth stage juvenile can withstand desiccation for a long time, sometimes 20 years or more. These nematodes clump togeth- er in a cryptobiotic state to form “nematode wool” when the plant tissue begins to dry. The wool can often be observed on the seeds in heavily infested pods and in dry plant debris. The presence of the infective fourth stage juveniles in seed and dry plant material is important in the passive dissemination of the nematode over long distances. The nematode in its desiccated state can survive passage Garlic bulb infected with the quarantine nematode, through pigs and cattle on infected seed. Although D. dipsaci is Ditylenchus dipsaci (From Nemapix Vol.2 1999 Eisen- back & Zunke eds.). regarded as a parasite of higher plants, it was reported that a Cali- fornian population of D. dipsaci from Allium sativum (garlic) could reproduce on soil fungi (Verticilium and Cladosporium) under laboratory conditions. It is also known that D. dipsaci is of potential economic importance on Agaricus bisporus (mushroom).