Effect of phosphonate fertilizers on egg hatching of M. javanica and M. incognita: The treatment of egg masses of M. javanica and M. incognita with 0.5% Calphos® and 0.5% Magphos® inhibited J2 hatching even after seven days of exposure. Inhibition of J2 hatching by Calphos® and Magphos® continued for five days after transferring of the treated egg masses to fresh water for both RKN species. No hatching was observed in Vydate L® treated egg masses, however, J2s hatched when these egg masses were transferred to water for an incubation period of one week. Phosphoros® did not affect egg hatching; a total of 153, 339 and 490 J2s of M. javanica and 231, 389 and 492 J2s of M. incognita hatched from egg masses exposed to 0.5% Phosphoros® for two, four and seven days, respectively (). Furthermore, J2s hatched from egg masses of M. javanica and M. incognita treated with water only and reached 457 and 541, respectively. Treated egg masses of M. javanica and M. incognita with 0.5% calcium phosphonate and 0.5% magnesium phosphonate, the main components of the tested fertilizers, inhibited egg hatching even after seven days of incubation. No egg hatching occurred when egg masses of both RKN species were transferred to fresh water even after five days of incubation. However, 292 and 427 J2s hatched when M. javanica and M. incognita egg masses were treated with 0.5% potassium phosphonate for one week, respectively (). J2s hatched from M. javanica and M. incognita egg masses treated with water only and reached 254 and 1325 J2s, respectively.
Effect of fertilizers and their chemical components on J2s emerging from eggs of Meloidogyne javanica and M. Incognita at different exposure times.
Effect of phosphonate fertilizers on J2s mortality of M. javanica and M. incognita: Calphos® and Magphos ® treatments caused 100% mortality of M. javanica and M. incognita J2s after one day of exposure. Mortality was lower when J2s were exposed to 0.5% Phosphoros®. Similarly, Vydate L® has the same nematicidal effect on the J2s as Calphos® and Magphos. J2s of both RKN species, exposed to 0.5% Calphos®, 0.5% Magphos® or Vydate L® did not recover i.e. did not resume mobility after being transferred to water in comparison to controls. Mortality in 0.5% Phosphoros® treated J2s was low even after three days of exposure (). Similarly, 100 % mortality resulted from the first day of exposure when J2s of both RKN species treated with 0.5% calcium phosphonate or with 0.5% magnesium phosphonate. None of the J2s of both RKN died after one day when they were placed in 0.5% potassium phosphonate or water, whereas, few J2s died after three days of exposure (). J2s of both nematode species, exposed to 0.5% calcium phosphonate or 0.5% magnesium phosphonate did not resume mobility after being transferred to fresh water.
Effect of fertilizers and their chemical components on J2s mortality of Meloidogyne javanica and M. incognita at different exposure times.
Morphological changes of J2s of M. incognita exposed to phosphonate fertilizers: Examining M. incognita within 2 days of exposure to the fertilizers revealed that no changes appeared in the length or width measurements of the treated J2s whereas, changes were observed along the esophagus and intestine of J2s treated with 0.5% Calphos® and 0.5% Magphos®. J2s exposed for six hours to 0.5% Calphos® or 0.5% Magphos® were dead, however, J2s treated with 0.5% Phosphoros® or water were alive even after three days of treatment. After 6 hours of exposure, no observable changes were detected in the esophageal region of J2s in all treatments. However, there were vacuoles present on small regions of the intestine of J2s exposed to 0.5% Calphos®. Magphos® (0.5%) treated J2s had small regions of intestine that had deteriorated. Intestine of J2s treated with 0.5% Phosphoros® appeared normal as the untreated ones with dense cells and without vacuoles. After 24 hours of exposure, only small degeneration appeared in the anterior part including the stylet and the esophagus of 0.5% Calphos® treated J2s. No changes were observed in the esophageal region of the nematodes in the other treatments. Large vacuoles were observed along the intestine of J2s exposed to either 0.5% Calphos® or 0.5% Magphos®. Moreover, a constriction was noticed in the intestine of 0.5% Calphos® treated nematodes. Normal intestines were found in J2s exposed to either 0.5% Phosphoros® or water. After 2 days of exposure, the esophagus of every nematode exposed to either 0.5% Calphos® () or 0.5% Magphos® () exhibited a complete deterioration. Normal esophagi appeared in J2s treated with 0.5% Phosphoros® and water only (). The intestine was completely degraded in nematodes exposed to 0.5% Calphos® and 0.5% Magphos® and vacuoles were abundant along the intestinal region (1, A2, B1, B2). Normal intestine was noticed in 0.5% Phosphoros® and water only treated J2s (1, C2, D1, D2).
Anterior part of the J2s of M. incognita exposed for 48 hours to A: Calphos®; B: Magphos®; C: Phosphoros®, and D: Water (the scale bar of A, B, C, D was 20 μm).
Fig. 2 Intestinal region of J2s of M. incognita exposed for 48 hours to A1 and A2 Calphos®; B1 and B2 Magphos®; C 1 and C2 Phosphoros®, and D1 and D2 Water only (the scale bar of A1, B1, C1, D1 was 20 μm whereas for A2, B2, C2, (more ...)
Effect of phosphonate fertilizers on root galling of tomato and egg mass production of M. javanica and M. incognita: Results showed that the reduction of root galling caused by M. javanica treated by Magphos®, Phosphoros® and Calphos® was 98, 66, and 47%, respectively compared with the untreated control (P= < 0.0001). No galls were found on roots of tomato plants treated with the nematicide Vydate L® (). The average numbers of egg masses produced on tomato roots inoculated with M. javanica were significantly lower (P= 0.0001) in pots treated with the phosphonate fertilizers than the untreated pots. The lowest numbers of egg masses was produced in plants treated with the phosphonate fertilizers. Magphos® treatment resulted in the lowest numbers of egg masses and consequently the lowest value of the reproductive factor in comparison to Calphos® and Phosphoros® (P= 0.0001) (). On the other hand, the Phosphoros® fertilizer treatment produced the highest tomato foliage weights which were significantly higher than those of the other two fertilizers and the untreated plants. Application of Vydate L® and Magphos® significantly (P = <0.0001) reduced the foliage weights. Root weights of Magphos® and Calphos® treatments were lower than the untreated roots (). The number of galls formed by M. incognita on tomato roots in all treatments was higher than those infected with M. javanica, alone. However, the effect of Magphos® treatment was similar to the results obtained on M. javanica since pots treated with Magphos® resulted in the lowest number of roots galls (P = 0.0029); this attributed to a total gall reduction of 84%. In contrast, gall numbers in tomato roots treated with Calphos® and Phosphoros® were lower than the control, 47% and 39% respectively; however, these differences were not significant. No galls were formed in tomato roots treated with Vydate L® (). The reproduction of M. incognita females expressed as egg masses was the lowest (P = 0.0082) when soil was amended with Magphos® followed by Phosphoros®. Calphos® soil amended resulted in lower number of egg masses when compared with untreated soil with no significant differences. The number of egg masses produced reflected the reproductive factor values (). On the other hand, the plants treated with Phosphoros® resulted in higher foliage weights compared with the other two fertilizers applications and untreated plants. Calphos® increased the foliage weight but was not significantly different from untreated plants. Magphos® decreased the tomato foliage weights but with no significant difference from the untreated plants. Tomato root weights were higher for plants treated with Phosphoros® and Vydate L® in comparison with all the other fertilizers ().
Table 4 The effect of Calphos®, Magphos® and Phosphoros® on foliage and root weight of tomato plants (cv GS12) infected with M. javanica and M. incognita, and root galling of tomato roots egg mass production and reproductive factor of (more ...)