structural:scholar_edition, quality:correction, information:filtering, quality:corruption
Pests

The sting nematode, Belonolaimus gracilis and the awl nematode, Dolichodorus spp. are both ectoparasites that can injure collard. Root symptoms include stubby or coarse roots that are dark at the tips. Shoot symptoms include stunted growth, premature wilting, and chlorosis (Nguyen and Smart, 1975). Another species of the sting worm, Belonolaimus longicaudatus, is a pest of collards in Georgia and North Carolina (Robbins and Barker, 1973). B. longicaudatus is devastating to seedlings and transplants. As few as three nematodes per 100 g (3.5 oz) of soil when transplanting can cause significant yield losses on susceptible plants. They are most common in sandy soils (Noling, 2012).

The stubby root nematodes Trichodorus and Paratrichodorus attach and feed near the tip of collard's taproots. The damage caused prevents proper root elongation leading to tight mats that could appear swollen, therefore resulting in a "stubby root" (Noling, 2012).

Several species of the root knot nematode Meloidogyne spp. infest collards. These include: M. javanica, M. incognita and M. arenaria. Second-stage juveniles attack the plant and settle in the roots. However, infestation seems to occur at lower populations compared to other cruciferous plants. Root symptoms include deformation (galls) and injury that prevent proper water and nutrient uptake. This could eventually lead to stunting, wilting and chlorosis of the shoots.

The false root knot nematode Nacobbus aberrans has a wide host range of up to 84 species including many weeds. On Brassicas it has been reported in several states, including Nebraska, Wyoming, Utah, Colorado, Montana, South Dakota, and Kansas (Manzanilla-López et al., 2002). As a pest of collards, the degree of damage is dependent upon the nematode population in the soil.

Some collard cultivars exhibit resistance to bacterial leaf blight incited by Pseudomonas cannabina pv. alisalensis (Pca).