What are the symptoms of banana Panama disease?

The first records of this disease were in Australia in 1876. The disease is so virulent that in the early 20th century it killed nearly every banana plant in Suriname.

In 1931, Scottish agronomist Clause Wardlaw found Panama disease in 15,000 acres on Jamaica and 50,000 acres in Panama, from which it derives its name.

The first external symptoms of Panama disease are a yellowing of the oldest leaves or a longitudinal splitting of the lower portion of the outer leaf sheaths on the pseudostem of plants that are usually more than 4 months old.

Yellowing begins with the oldest and progresses to the youngest leaves of the plant. This is followed by wilting and buckling of leaves at petiole base. As the disease progresses younger and younger leaves collapse, until the entire canopy consists of dead or dying leaves.

However, fruits are not infected and are not discolored. This distinguishes fusarium wilt of banana from bacterial wilt of same plant. Panama disease presently is controlled through the use of resistant (Cavendish) varieties.
What are the symptoms of banana Panama disease?

What are the reasons for crop rotation?

The term ‘crop rotation’ is defined as a systematic rotation of corps in the same field and at a limited length in time. The reason to institute a rotation plan can be summed up: to create a healthy farm system. It will increase a farm’s productivity over the course of many seasons.

For example, in sugar beet production the main reason for crop rotation are:
*To increase active organic matter in the soil
*To make more efficient use of available plant nutrients in the soil
*To aid in control of harmful weeds, insects and nematodes

Crop rotation help prevent the buildup of weeds adapted to particular cropping system. Certain weeds are more common in some crops than others.

Pigweed, lambs squatter, common ragweed, velvetleaf, cocklebur, foxtail species and crabgrass are found in summer –cultivated crops such as corn.

A good rotation will decrease soil-borne disease and pest outbreaks. These two pressures on the organic farm are often the primary motivation for growers to create a rotation, as the damage of one outbreak can decimate several cash crops in just a few days.

Another reason is to build up and maintain soil fertility. Each crop differs in the amounts of nutrients it needs from the soil and in what it gives back to the soil.

Crop rotation historically was very important for managing weed problems. Today, rotation is used more for managing disease and insects than weeds.
What are the reasons for crop rotation?