Using chemicals not specifically recommended for garden crops. Storing leftover diluted spray. Use 2 to 3 pounds of complete fertilizer per 100 square feet in absence of soil test. Plants growing in compacted, poorly drained soil Modify soil with organic matter, coarse sand. Provide surface drainage.
Iron deficiency Apply iron to soil or foliage.
Low temperature Plant at proper time. Do not use light-colored mulch too early in the season. Inadequate phosphorus Apply phosphorus at soil test recommendation. Damage by insects Use recommended insecticide treatment. Plant disease Use resistant varieties, remove diseased plants when noticed and use recommended control treatments.