Two field and greenhouse diseases of Prosopis (mesquite)

Canker and tip-dieback diseases have been found in field and greenhouse plantings of Prosopis being examined in agroforestry trials in South Texas. Several fungal species were associated with the field cankers, most notably a Lasiodiplodia and a Pestalotiopsis. In the greenhouse, a tip-dieback as well as a canker disease that began at pruning cuts on the stock plants was seen. Pestalotiopsis was most commonly isolated from these plants. Isolated cultures of the Lasiodiplodia and the Pestalotiopsis together with several other often associated fungi, (including Alternaria and Fusarium) were tested for pathogenicity on young mesquite plants. Only Lasiodiplodia and Pestalotiopsis produced cankers under the conditions tested when spores were applied using wound inoculation techniques. Pestalotiopsis required high wound inoculation techniques. Pestalotiopsis required high humidity and proved much less damaging than Lasiodiplodia, which closely mimicked the field symptoms. Benlate was found to give the greatest growth inhibition of these fungal pathogens in in vitro fungicide tests.