Control of manganese deficiency in field peas grown for seed or human consumption

SUMMARYThe effect of foliar applications of different formulations of manganese on pea yield and ‘marsh spot’, a seed defect which reduces quality of peas (Pisum sativum) grown for human consumption or seed was evaluated in nine experiments in the East of England from 1992 to 1994. Sprays, at dose rates recommended by the manufacturer, were applied to field peas, cvs Maro or Bunting, on three occasions at the four node pea growth stage, first pod and 14 days later, or on two occasions at first pod stage and 14 days later. Although the sites selected had a previous history of marsh spot in pea crops, there were no visual foliar symptoms of manganese deficiency in peas grown in any year at any site. Applications of manganese did not increase yields compared with untreated peas and there was no effect on maturity. Marsh spot was negligible in untreated peas at sites where soils had the lowest levels of manganese (22 and 44 mg/kg), thus soil analysis for manganese may be inappropriate as a guide to prediction of marsh spot problems. The three spray programmes, which included an early application of manganese at the 4–5 node stage, gave no statistically significant improvements in marsh spot control. There was a good correlation between amounts of manganese applied and reductions in marsh spot, and manganese sulphate, 31% w/w at 3·1 kg/ha applied as a split dose, achieved the best control. An exception was the manganese carbonate 50% w/v formulation which may have been poorly assimilated by the plant. Chelated manganese as MnEDTA 6·4% w/v at the rates recommended by the manufacturer was inadequate for control of marsh spot in all years.

Correction of iron deficiency in peas by foliar sprays

A severe iron deficiency in peas grown on grey to black clay loam soil overlying limestone (rendzina) was successfully ameliorated by foliar application of ferrous sulphate. Two applications, three weeks apart, increased the fresh weight of peas harvested by more than 100 per cent (P < 0.001). The two sprays also increased the numbers of pods, dry weight of the pods, fresh weight per pea and maturity of the peas (all P < 0.001), and herbage yield (P < 0.01). One application of iron sulphate was insufficient to arrest completely the symptoms of iron deficiency. The peas did not show vegetative or marsh spot symptoms of manganese deficiency, and there were no significant changes in measurements to manganese sprays.

Evaluation of glassy frits as micronutrient fertilizers. II. Manganese frits.

In pot and field tests MnSO4 and the frits FTE Z 4 (13 % Mn), HZ 1 (15.9 % Mn) and HZ 17 (21 % Mn) increased reducible soil Mn for at least 1 1/2-2 years. Mn content of pasture increased four-fold in the first cut after application of 400 kg/ha MnSO4 but sharply decreased in later cuts and became negligible by the second year. 400 kg/ha HZ 17 did not affect pasture Mn. In peas 400 kg of soil- or foliar applied MnSO4 controlled marsh spot better than 800 kg HZ 1; spraying at the middle and again at the end of the blooming stage gave the best control. With sugar beet, soil dressings of MnSO4, HZ 1 and HZ 17 equally increased yield, sugar production and leaf Mn, and decreased incidence of Mn deficiency. When the rates of these fertilizers were increased from 100, 179 and 86 kg respectively to 400, 714 and 343 kg, sugar production was not significantly improved; leaf Mn and incidence of deficiency symptoms responded to the higher Mn rates. Soil application was rather better than foliar treatment. No treatment controlled Mn deficiency throughout the entire season. The % of Mn-deficient plants was related, negatively, to leaf and reducible soil Mn, but not to yield. Soil-applied Mn did not control gray spot in oats or increase yields but sprayed Mn did. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The movement of manganese in the plant and the practical consequences.

Movement of foliar applications of Mn was investigated. Mn applied to the leaf was translocated to other parts of the plant via the roots; in the leaf, upward movement predominated. Redistribution of Mn from the roots was insufficient to prevent Mn deficiency in the foliage formed after spraying; where the soil Mn supply was insufficient, repeated spraying was necessary. In wheat, oats and sugar-beet, spraying was best done as soon as Mn deficiency symptoms became evident, and again 4 weeks later. Control of marsh spot of peas was best achieved by spraying at mid-bloom and again just after flowering.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)