Suppressiveness of Soil Amendments with Pelleted Plant Materials on the Root-knot Nematode Meloidogyne Incognita.

Soil treatments with formulated plant biomasses or waste materials can be an effective alternative to green manure crops for a sustainable management of root-knot nematode infestations. The suppressive performance of soil amendments with three commercial formulations of defatted seed meal from Brassica carinata, dry biomass of Medicago sativa and pressed pulp from Beta vulgaris was comparatively evaluated on the root knot nematode Meloidogyne incognita both on potted and field tomato (cv. Regina) trials. Products were applied at rates of 10, 20, 30 or 40 g/kg and 20 and 40 T/ ha soil in pots and field, respectively. Soil non treated or treated with the nematicide Oxamyl were used as controls in both experiments. Amendments in potted soil significantly reduced M. incognita infestation on tomato roots compared to both the untreated control and treatment with Oxamyl, also increasing tomato plant growth up to the 30 g/kg soil rate. At the end of the field tomato crop, soil population density of M. incognita resulted significantly reduced by all the tested treatments, whereas tomato yield was significantly higher than the untreated control only at the lowest amendment rate. Soil amendments with the materials tested in this study demonstrated to be a potential additional tool for a satisfactory and safe management of root-knot nematodes.

The use of olive mill wastes for the control of root-knot nematodes.

The suppressive effect of olive mill wastes was tested in a field experiment in sandy soil, infested by Meloidogyne incognita, in the Province of Lecce, southern Italy. The field was subdivided in 12 m2 plots distributed at random in four blocks. Treatment consisted of different dosages (10, 20 and 40 t/ha) of two composts prepared with either exhausted or fresh olive pomace or raw extraction sewage at rate of 40 or 80 m3/ha. There were four untreated control plots and four plots on which the granular 5% formulation of fenamiphos had been broadcast incorporated into the soil at the rate of 300 Kg/ha, one week before planting the tomato cv. Tondino di Zagaria. All treatments statistically increased tomato yields with respect to the control. Conversely, the root gall index, assessed according to a scale from 0 (no gall at all) to 5 (root system of reduced size and deformed by large galls), was significantly reduced in all treated plots. Also soil populations of the root-knot nematode declined, significantly compared to the control, except in the soil treated with the lowest doses of raw sewage or exhausted pomace compost.

Efficacy of the liquid formulation of some nematicides.

Bunches of 25 g of tomato galled roots containing ca. 270 eggs and juveniles/g of Meloidogyne incognita were buried on 29 September 2001 in gauze bags at the depth of 15, 30 and 45 cm in a sandy loam. The liquid formulation of the nematicides 1,3 dichloropropene (at the rate of 100, 200 and 300 l/ha), metam sodium (at the rate of 500, 1000, and 1500 l/ha), oxamyl (at the rate of 50, 100 and 150 l/ha) and fenamiphos (at the rate of 30, 60, and 90 l/ha) were then applied in 10, 20 or 40 l/m2 of water. Control plots received only plain water. One month later all bags were recovered and the roots mixed with steamed soil and filled in plastic pots in which two tomato seeds were planted. Fifty days later plants were uprooted and aliquots of roots were macerated in blender to determine the number of eggs and juveniles. 1,3 dichloropropene, metam sodium and oxamyl were equally effective in controlling root-knot nematodes; fenamiphos was less effective. For all chemicals degree of control increased with the increase of rate of application and the volume of water of application, but decreased in the increase of depth of nematode burial.

Control of Pratylenchus vulnus in stone fruit nurseries.

Almond, peach and olive nurseries were prepared in sandy soil infested by Pratylenchus vulnus in southern Italy. Soil treatments before or at sowing included methyl bromide at the rate of 40 g/m2; 1.3 D at the rate of 15 ml/m2; dazomet at the rate of 100 g/m2 without plastic tarping, or at the rate of either 100 or 50 g/m2 with tarping, and fenamiphos Gr 5 at the rate of 100 g/m2 or 240 CS at the rate of 40 g/m2 as single application; fenamiphos Gr 10 and 240 CS were also applied at planting and two, four and six months after sowing, each time at the rate of 10 g/m2. The experiment was discontinued ten and thirteen months after sowing, respectively for olive and peach and almond. Methyl bromide, 1.3 D or fenamiphos, or dazomet, under certain circumstances, produced agronomically suitable plants, but none of the treatments eradicated the nematode.

Influence of Aldicarb and Fenamiphos on Tylenchulus semipenetrans Population Densities and Orange Yield.

The effect of aldicarb and fenamiphos on Tylenchulus semipenetrans population densities and on orange yield was investigated during a 3-year (1986-88) field trial in Italy. Rates were 10 and 20 kg a.i./ha as an early spring single application, 5 kg a.i./ha in spring and 5 kg after flowering, and 5 kg a.i. in spring followed by 2.5 kg/ha after flowering and 2.5 kg/ha in early autumn. Rates and times of application of the two nematicides did not affect numbers of females of T. semipenetrans on the roots but suppressed (P = 0.05) egg, male, and second-stage juvenile population densities from October 1986 to 1988. Yield of fruit was not affected by any treatment during 1986-87. Yield was increased (P = 0.05) in 1988 by i) a single application of 20 kg a.i./ha aldicarb, ii) 10 kg a.i./ha fenamiphos, and iii) an application of 5 kg a.i. aldicarb/ha in spring, followed by two more applications of 2.5 kg/ha each in June and September. Fruit size was not affected by the nematicide treatments. Concentrations of fenamiphos and its metabolites, in rind and pulp, were below 0.02 ppm.

Damage to Italian Crops caused by Cyst-forming Nematodes.

Investigations were undertaken in 1982-88 to estimate yield losses of carrot, sugarbeet, wheat, and potato caused by cyst-forming nematodes (Heterodera and Globodera species) in several provinces of Italy. Soil samples were collected at planting in 0.5-ha sampling areas distributed in each crop's major production area. Yield loss estimates were based on nematode population estimates and on curves derived earlier relating nematode densities with crop yields in Italy. Estimated yield loss values were based on the average prices reported for Italy in 1989. Heterodera carotae caused carrot yield losses in the Foggia (20%) and Venice (12%) provinces. Heterodera schachtii was common in our samples, but sugarbeet yield losses were highest in the province of L'Aquila (21%), followed by Ferrara (4.2%), Ravenna (3.3%), Modena (2.7%), and Rovigo (2.6%). Globodera rostochiensis and G. pallida were widespread in only a few of the major potato growing areas, but yield losses are remarkably high at Forli (17%) followed by Bari (9%), Catanzaro (6%), Foggia (3%), and Trento (3%). Heterodera avenae was common on wheat in the sampled provinces, but caused less than 1% yield reductions. Values of total estimated yield losses were 21.1 billion (Italian liras) for potato, 13.8 billion for sugarbeet, 3.2 billion for carrot, and 2.6 billion for wheat.

Efficient Procedure for Extracting Tylenchulus semipenetrans from Citrus Roots.

Investigations were undertaken to determine the suitability of sucrose and magnesium sulphate solutions and a silica colloidal suspension with centrifugation for extracting Tylenchulus semipenetrans from citrus roots. The efficiency of incubation, sodium hypochlorite, centrifugation, and maceration methods was also compared. Numbers of females recovered by centrifugation with colloidal silica were greater than those from sucrose or magnesium sulphate. Incubation, sodium hypochlorite, and centrifugation methods were satisfactory for extracting eggs, second-stage juveniles, and males, whereas the maceration-sieving method was less efficient. Combining the sodium hypochlorite method with a 15-second maceration followed by centrifugation in colloidal silica reduced the recovery of T. semipenetrans females from citrus roots.