This paper presents the results from a survey that was carried out to determine the host plants of tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in five States in Sudan. This survey was carried out in greenhouses and open‐field vegetable production areas between the years 2011 and 2014 using pheromone traps. The survey showed that the main host plant of T. absoluta is tomato (Lycopersicon esculentum), but it also attacks potato (Solanum tuberosum), eggplant (S. melongena) Jimson weed (Datura stramonium) and S. dubium in the family Solanaceae, and broad bean (Vicia faba) and alfalfa plant (Medicago sativa) in the family Fabaceae. This paper is the first record of the following plans being hosts for T. absoluta: Watermelon (Citrullus lanatus) in the family Cucurbitaceae, Physic nut (Jatropha curcas) in the family Euphorbiaceae, spiny amaranth (Amaranthus spinosus) in the family Amaranthaceae, Ramtouk (Xanthium brasilicum) in the family Asteraceae and S. dubium. The study showed that the leafminer male numbers and the symptoms were significantly increased in S. melongena and S. dubium after severe damage and complete loss of the main host, the tomato crop and these two species may be the preferred alternative host plants.
SummaryWeeds are a major constraint to increasing production of lentil (Lens culinaris Medik.) in Sudan, Field studies were conducted to determine the yield loss due to weeds, to identify the critical period of weed interference, to evaluate the activity of different herbicide mixtures in controlting weeds and their selectivity for lentil, and to evaluate different methods of weed control for developing an integrated weed management practice. At Rubatab. unrestricted weed growth accounted for up to 84% loss in yield. The critical period of weed control was between 2 and 4 weeks after sowing. However, a weeding regime experiment at Dongola, a cooler location with a longer growing season, indicated that the critical period was between 4 and 6 weeks after sowing. suggesting that the critical period might vary with the environmental conditions. The herbicides imazethapyr (0.05 kg a.i. ha‐1), terbutryn (1.0 kg a.i. ha‐1) and prometryn (1.0 kg a.i. ha‐1), each in a tank mixture with pendimethalin (1.2 kg a.i. ha‐1), were tolerated by lentil, controlled weeds effectively and significantly increased yields at Wad Hamid. Their efficacy in controlling weeds at Rubatab was low, however, because of the presence of Tephrosia apollinea (Del.) DC. and Melilotus indica (L.) All., which tolerated these herbicides. Efficacy was also reduced in heavier soils. One supplementary hand‐weeding at 4 weeks after sowing enhanced the performance of these herbicides under such conditions. A tank mixture of oxyfluorfen (0.24 kg a.i. ha‐1) with either terbutryn (1.0 kg a.i. ha‐1) or prometryn (1.0 kg a.i. ha‐1) also provided good weed control and increased yield of lentil at Wad Hamid. Application of a higher dose (1.5 kg a.i. ha‐1) of terbutryn and prometryn caused phytotoxicity. Irrigation before seed‐bed preparation reduced grass and broad‐leaved weeds by 58% and 40% respectively, and gave a 30% increase in grain yield over no irrigation. Pre‐emergence application of oxyfluorfen (0.24 kg a.i. ha‐1) and a supplementary hand‐weeding at 4 weeks after sowing gave excellent control of weeds and increased lentil yield by 57% over the weedy control. Thus, use of presowing irrigation, pre‐emergence herbicide and one hand‐weeding form an effective integrated package for controiling weeds in northern Sudan.
An outbreak of larvae and adults of a devastating moth was noted to be causing severe damage in tomato grown in greenhouses at Khartoum State, Sudan during June 2010. Symptoms included foliage mining and leaves drying. Photographs of symptoms and larvae and adults of the pest (and subsequently specimens) were sent to Russell IPM, UK and the Finnish Museum of Natural History for identification. The pest was identified as Tuta absoluta (Meyrick), (Lepidoptera: Gelechiidae). This is the first official record of T. absoluta in Sudan, based on surveys in tomato production areas in Khartoum, Gezira, Red Sea and North Kordofan States and eggplant and potato in Khartoum State. Severe yield loss due to the serious feeding damage on foliage and fruits infestation was reported on tomato and eggplant fields at Khartoum State.
Common bean is an important food legume crop in Sudan. Drought and heat stress are considered the main factors responsible for low productivity. Nine common bean genotypes were evaluated for yield stability under different sowing dates and watering regimes in three field experiments conducted in the River Nile State-Sudan during 2003 to 2006. 10 test-environments were thus achieved, representing the combined effect of drought and heat stress. Stability analysis (Eberhart and Russel model) was performed to identify the most yield-stable bean lines under limited moisture and temperature stress. The genotypes Bellenber-1, COWU-3-94-9, S/Hashim/98 and the small seeded genotype DB 190-74-1, appeared to be the most stable. It was concluded that these genotypes can be used to improve common bean tolerance to drought and heat stress conditions in the Sudan.
A field trial was conducted at Hudeiba Research Station Farm,River Nile State, Sudan, during 2001/2002, 2002/2003 and 2003/2004winter seasons. The objective was to evaluate the activity and selectivityof three pre-emergence herbicides for weed control in wheat. Theherbicides treatments were pendimethalin (Stomp) at 1.2, 1.8 and 2.4 kga.i. ha-1, oxyfluorfen (Goal) at 0.24, 0.36 and 0.48 kg a.i ha -1 andoxadiazon (Ronstar) at 0.72, 1.08 and 1.44 kg a.i ha -1 . The prevailingweed species in the experimental sites were Ipomoea sp, wild mustard(Sinapis arvensis L.), common beet (Beta vulgaris L.), sweet signal grass[Brachiaria eruciformis (Sm)] and Bermuda grass [Cynodon dactylon (L.)Pers.]. The results showed that the losses in grain yield of wheat, due toweeds competition, were 37%, 29% and 21% for seasons 2001/2002,2002/2003 and 2003/2004, respectively. The herbicide pendimethalin, atall rates tested, showed no phytotoxicity symptoms on wheat. The higherrates of oxadiazon and oxyfluorfen, however, showed slight phytotoxicityto the wheat crop. All herbicide treatments of Ronstar and Goal resultedin good to excellent control (72%–97%) of both grassy and broad-leavedweeds. The herbicide pendimethalin displayed excellent activity againstgrasses and poor to satisfactory activity (0%-67%) against broad-leavedweeds. The weed Cynodon dactylon tolerated all herbicide treatments.With the exception of Stomp, all herbicide treatments significantlyincreased wheat grain yield compared to the weedy check.
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