Can Agricultural Practices in Strawberry Fields Induce Plant-Nematode Interaction towards Meloidogyne-Suppressive Soils?

The importance of benign approaches to manage the root-knot nematodes (RKNs, Meloidogyne spp.) in strawberry farms has become more evident with increasing strawberry production and export in Egypt. Therefore, data accumulated on biosolarization and soil amendments to favor beneficial microorganisms and maximize their impact on RKN management are built on a robust historical research foundation and should be exploited. We examined RKN population levels/parameters in three strawberry export governorates, six farms per governorate, to characterize the exact production practices that are responsible for RKN-suppressive soils. All selected farms enjoyed soil biodisinfestation resulting from incorporating organic amendments followed by a plastic cover to suppress soil pathogens. Various safe and inexpensive agricultural practices in the El-Ismailia and El-Beheira governorates were compared to the toxic and expensive fumigants that could eliminate RKNs in the Al-Qalyubia governorate. Two farms at El-Ismailia were of special interest as they ultimately showed almost zero counts of RKNs. The two farms were characterized by incorporating cow manure [containing 0.65% total nitrogen, 21.2 carbon to nitrogen (C/N) ratio] and poultry manure (0.72% total nitrogen, 20.1 C/N ratio) followed by soil solarization via transparent, 80-µm thick plastic covers for 60−65 summer days as pre-strawberry cultivation practices, and similar covers were used after transplanting. Typically, the longer the pre-plant soil solarization period with thicker transparent plastic covers, the better it could suppress the RKN population densities in the tested farms. Their soils were characterized by relatively high pH and low electrical conductivity. The significant development in biocontrol genera/species abundance and frequency could explain the lower (p < 0.0001) RKN population levels inhabiting the farms of El-Ismailia than the El-Beheira governorate. These factors could provide the first approximation of key practices and factors that could collectively contribute to distinguishing and exploiting soil suppressiveness against RKNs. We discussed edaphic properties and production practices that could modulate populations of natural RKN antagonists for sustainable strawberry cultivation.

Application of Bacillus species for controlling root-knot nematode Meloidogyne incognita in eggplant

Background

Eggplant (Solanum melongena L.) is one of the important vegetable crops infected by Meloidogyne incognita all over the world, including Egypt. Chemical nematicides frequently cause environmental pollution and toxic hazards to human, plants, and animals; certain biocontrol agents that are environmentally friendly and safe to humans and animals were tested against the root-knot nematode Meloidogyne incognita in eggplant.

Objective

This work is aimed to determine the nematicidal activity of Bacillus spp., viz., B. subtilis and B. pumilus, against M. incognita in three separated experiments to study their ability in controlling M. incognita and in improving the growth parameters of eggplants. Bacillus spp. were applied as single or in combination (experiment I), single treatment at different doses (experiment II), and different times (three times) of application (experiment III).

Results

The results of experiment I revealed that Bacillus sp. + B. subtilis significantly reduced the second-stage juvenile (J2) in soil and galls and egg masses in roots, while Bacillus sp. + B. pumilus significantly reduced J2 in roots. Bacillus spp. in pairs were more effective against M. incognita. In experiment II, Bacillus sp. (40 ml) significantly reduced the J2 in soil and galls and egg masses in roots, while B. pumilus (40 ml) significantly reduced the J2 in roots. The nematicidal activity of Bacillus spp. was increased by increasing the applied dose. In experiment III, B. subtilis, when applied three times, significantly reduced the J2 in soil and the J2 and galls in roots, while B. pumilus (applied three times) significantly reduced the egg masses in roots. All Bacillus spp. treatments highly increased the tested growth parameters compared to the controls.

Conclusions

The tested biocontrol agents used more than once or in combination are more effective than those used only once in controlling nematode parameters in eggplant under greenhouse conditions with a consequent increase in eggplant growth. These bacterial isolates need to be studied under different field conditions for confirmation.

Effect of certain organic amendments and Trichoderma species on the root-knot nematode, Meloidogyne incognita, infecting pea (Pisum sativum L.) plants

This study was conducted to evaluate the effects of three fungal species, Trichoderma harzianum (Th), T. viride (Tv), and T. vierns (Tvi), and ground seeds of fennel (Foeniculum vierns) and caraway (Carum carvi), and powdered leaves of basil (Ocimum basilicum) as soil amendments against the root-knot nematode, Meloidogyne incognita on pea root, Pisum sativum under screen house conditions. The treatments were compared to a nematicide, carbofuran 10G, and untreated check. The tested materials significantly (P ≤ 0.05) reduced M. incognita on pea as indicated by the numbers of galls, egg masses, and J2 per root system in pots, either as single or combined treatments. The combined treatments caused higher average total percentages of nematode reduction than those achieved by single ones. The single treatments recorded the averages total percentages of nematode reduction ranged from 72.4 to 82.0%. Basil waste as single was superior in reducing nematode numbers of J2 and egg masses in root system per plant, as it achieved the highest average total percentages of nematode reduction (77.9%) than 73. 9 and 72.4% caused by fennel and caraway, respectively. In combined treatments, the average total percentages of nematode reduction ranged from 72.4 to 86.4%. Basil + (Th) caused the highest reduction (86.4%), followed by caraway+Tvi (86.3%) and caraway+Th (86.2%). The nematicide, carbofuran was as effective as most as the treatments in reducing nematode parameters. Also, the treatments highly increased growth and yield criteria of pea infected with M. incognita as indicated by shoot length and fresh and dry weights and root fresh weight, number and fresh and dry weights of pods.