Epidemiologia da ferrugem asiática da soja em ambientes do Estado de Goiás: efeito de fungicida e época de semeadura
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2005-02-28
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Universidade Federal de Goiás
Resumo
During the last crops, the soybean rust has been appeared as one of the most important
problems in the national agriculture. The direct loses on the production and in the costs with
fungicides have been increased the damages on this crop. Aiming to understand better the disease
epidemiology, this work searched for answers by epidemic progress in two locations, the time of
planting effect, the cycle of planting, the use of fungicide, and by different cultivars. The
experiments were assembled in Experimental Stations from Agência Rural in Senador Canedo and
in Anápolis. For each place were used three times of planting, six cultivars on the three crop cycles
(Monsoy 6101 and BRSNina premature cycle; Emgopa 315 and BRSGO Santa Cruz middle
cycle; Emgopa 313 and BRSGO Paraíso late cycle), with and without fungicide action, have been
evaluated on the three parts of the plant (lower, middle and upper). Each time, to each one of the
places, have been considered as an experiment with spli-split-plot. After the disease symptom
observations, the split under chemical control were freaked each 21 days using
pyraclostrobin+epoxiconazole on 66,5 g + 25 g a.i. ha-1. The evaluations, after the first symptom
observation, have been done weekly up to the complete leaves took away. With the periodic
severity data the Area Under Progress Disease Curve (AUPDC) and Relative Area Under Progress
Disease Curve (RAUPDC), that is the area divided by the epidemic time duration, were calculated.
The parameters were productivity, thousand-grains weight (TGW) and small grains percent
(%SG). The delay on the start of the disease on Anápolis, comparing with Senador Canedo,
increases the discussion on the results. The previous disease occurrence in Senador Canedo and the
high level inoculate presented can be associated to the fact of experimental site in Senador Canedo
has soybean cultivate all over the year. The delay on the start of the disease on Anápolis, compared
to Senador Canedo has been resulted on productivity increase and fungicide effect decrease.
Comparing the time of planting in both planting places, the second one presented the highest level
of severity, but the highest level of productivity even. The use of fungicide decrease significantly
the AUPDC, increase the productivity, the TGW and decrease the %SG. The premature cycle
cultivars presented lowest disease severity. The cultivar Emgopa 315 although be a medium cycle
presented results equals premature cycles cultivars. On each site the time of planting were
differentiated. On high pressure inoculate condition the difference between evaluated factors was
lower. On lower inoculate pressure the evaluated factors expressed better the changes. As
conclusion we have: a) how early the disease appears higher is your effect on productivity; b) using
premature cultivars the escape effect decrease the disease damages when compared to medium and
late cycle; c) the disease decrease the soybean cycle by the defoliation; d) although all the cultivars
presented susceptibility to rust, related to lower severity on partial resistance; e) the fungicide
utilization pyraclostrobin+epoxiconazole on de 66,5 g + 25 g a.i. ha-1, used on first symptom and in
21 on 21 days decrease the disease progress and the effects on productivity; f) the disease progress
decrease by fungicide utilization is better in late planting; g) under the fungicide effect
pyraclostrobin+epoxiconazole with 66,5 g + 25 g a.i. ha-1 there s no variation time planting and
site; h) under high inoculate pressure the variation between time planting on disease progress and
productivity is lower; i) the time of planting must be considered but not lonely, always in
association with others factors of fungus action; j) the use of RAUPDC is necessarily when there is
variation the time of soybean cycle, affecting the rust epidemic duration; l) the highest disease level
occurs on the part of the plant near the soil and the defoliation difficult the disease evaluation on
this part of the plant; m) the most effective disease occurs on the highest parts of the plant.
Descrição
Citação
CRUVINEL, Adriane Reis. Epidemiology of soybean rust in different places on Goiás
State: fungicide and time of planting effect. 2005. 91 f. Tese (Doutorado em Ciências Agrárias) - Universidade Federal de Goiás, Goiânia, 2005.