Weeds


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Fall panicum (Panicum dichotomiflorum)

Fall panicum is one of the most common grass weeds found in the EAA. It is a summer annual with large round, smooth sheaths that are often bent at the nodes. It may reach 7 feet in height and is found throughout most of the United States in various agronomic and horticultural crops, turfgrass, nurseries, landscapes, and noncrop areas.

Identification

A primary identifying characteristic of this grass weed is the 'zigzagged' growth pattern it takes on due to bending at the nodes.

Seedling: Fall panicum seedlings are much different from the mature plants in that the seedlings have many hairs on the lower surface of the leaf blades. Leaves are rolled in the shoot, the ligule is a fringe of hairs to 2 mm in length, and auricles are absent.

Leaves: Rolled in the shoot, 15 to 20 mm wide, 4 to 20 inches long, and auricles are absent. The ligule is a fringe of hairs reaching 2 to 3 mm in length and is often fused at the base. Leaf blades have a conspicuous midvein and are smooth above but sometimes slightly hairy near the leaf tip or leaf base. The lower leaf surfaces of mature plants are without hairs (glabrous) and glossy

Stems are without hairs (glabrous), round, and sometimes glossy. Nodes along the stem are usually swollen and bent in different directions, which contributes to the rather unusual growth habit of this weed.

Roots: A fibrous root system with stems that are capable of rooting at the nodes.

Flowers: The seedhead is a wide, spreading panicle that develops a purplish tint when mature. Individual spikelets are yellow and approximately 3 mm long by 2 mm wide.

Identifying Characteristics: Fall Panicum is often mistaken for Johnsongrass (Sorghum halepense) or Barnyardgrass (Echinochloa crus-galli) prior to seedhead formation. However, johnsongrass has a membranous ligule unlike that of fall panicum and johnsongrass seedlings also do not have hairs on the lower leaf surface like those of fall panicum. Additionally, barnyardgrass does not have a ligule at all and barnyardgrass seedlings might only have hairs near the leaf base.

Control in Sugarcane

Fall Panicum can be controlled with preemergence applications of Prowl. Post emergence options include Asulox, Evik, and Envoke.

Ligule

Panicles

Seedling

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.

Paragrass, Urochloa mutica (Panicum purpurascens, Brachiaria purpurascens)

Paragrass, which is often referred to as known as ‘maiden cane’ in South Florida, is native to Africa . It is a perennial that grows best in moist to wet disturbed and cultivated areas. It is most common in ditches, but often moves into cultivated areas from infested ditch banks.

Identification:

It has a perennial (clumping) growth habit with stems that bends and form roots at the lower joints. When growing in the open the stems can reach 3 feet tall and when leaning through other vegetation, stems can be over 12 feet long. Stems are round in section. Joints are very hairy. Leaf blades are flat, smooth, 3/8 to 5/8 inch wide and 4 to 12 inches long. Leaf sheaths are hairy with pustule-based hairs. Seedheads have 8 to 20 branches that have an erect “signal flag” appearance. Flowers and seeds are located on the lower side of the branches, and the seeds are wrinkled.


Figure 1. Paragrass on the edge of a field. This species is typically found growing out of ditches into field edges.


Figure 2. 
Close-up of stem joint, showing the dense hairs typical of paragrass.

Control in sugarcane:

Paragrass is best controlled in sugarcane by spot treating with glyphosate.